"Smart" typically means what pop culture defines as smart...you're a scientist or something. But there's also things like street smarts. I know highly-paid businessmen who type with two fingers using the hunt & peck method, and make ten times the money that I do, so despite my keyboarding skills, I'm not really all that smart from that perspective, eh?
Yet I also know businessmen who make six figures & are living paycheck to paycheck, so you can be commercially successful, yet financially a failure. Smart is relative to the scene in question. There's a good book called "The Talent Code" that discusses what talent is & how to grow it; talent is basically a combination of your ability to do something (because not everyone can physically do certain things, like say win the Olympics) coupled with the speed or rate at which you can learn it. Child prodigies have a natural aptitude for learning particular things quickly, which is why you see things like 8-year-olds who can play the guitar like Elvis. Anyone can learn to play the guitar, it just take more time because you require more time to learn the instruments & memorize songs, but there's always that "wow" factor when someone learns it fast or learns it young or is amazing at something in public.
However, on the flip side, if you put in the time & effort to mastering something, then people will see you as naturally talented, instead of seeing all of the practice & work you put into learning something. This is a particularly bad trap for bright kids because they'll cruise along in their early years with life on easy mode, and then when they hit a point where they have to do real work & actually try hard & be persistent at something, they crash & burn because they've never had to do it before. This is where the phrase "bright, but undisciplined" comes from...the ability is there, but the daily work required to grow in that field wasn't put in consistently, or at all.
Hard work beats simply having talent any day, but talent plus hard work is pretty much the trump card that can't be beat. Just look at Michael Phelps or Lance Armstrong...they not only had the capacity to do their sport, but they also put in the work to master it & become the best. Politics also play a role at times. Like, Arnold had the right body for bodybuilding aesthetics, proportion-wise - he had the natural "ability" & then put in the work to get the body he wanted - and he won Mr. Olympia 7 times for it, even though there were technically people in better shape than he was at times, but he was marketable & grew to be famous & politically that also worked for him to win over & over again.
For most people in most situations, that's all BS anyway. All of you are here because you can operate a computer, you can type, you can read & write English, and want to communicate with like-minded people in an online environment because you're bored or lonely or whatever. Does it matter than you maybe can't type 200 words per minute? No, because you're still able to do the task in question. That's why a lot of races like Ironman aren't about winning, but rather about finishing & setting a new PR, or personal record, because you're basically competing against yourself at that point. You may simply not have the physical mechanics or lung capacity or whatever to complete a sub-8-hour Ironman event, but that doesn't mean you still can't compete & have a good time & be competitive.
So "smart" depends on the field, and you can be smart in some areas & royally dumb in other areas. Plus there are a lot of smart people who don't show it off publicly. Most people who are "smart" or are really good at something get that way because they spend a lot of time working on the right stuff to get good at it. Lots of effort & many years combine to create the persona that everyone sees as "smart". And a lot of really smart people are really bad when it comes to emotional intelligence. Elon Musk is a wildly smart dude, but his first wife said that one time he told her "If you were an employee, I'd fire you". From a seemingly smart guy, that's not the smartest choice of words when talking to someone you love.
There's a variety of other types of intelligence as well. One of my buddies isn't book-smart, but he can take apart, reassemble, and fix or make better anything he touches...engines, cars, boats, house projects, you name it. His mechanical aptitude is amazing, but if you put him in front of a textbook, he's not so good at that. Other people have lower IQ's & just struggle with the basics all their lives. I'm like that with math...I have a really hard time visualizing numbers. I can write a huge post on a some random topic, no problem, but give me a math problem beyond simple addition & I'm reaching for a calculator, haha. It's just not an aptitude I have, but I can make it work with a pencil & paper, a calculator, and maybe the Photo Math smartphone app, lol.