Intelligent and smart are the same. Smart is more informal. In an official report or scientific article, we would probably use "intelligent," and in everyday speaking, we would probably use "smart."
The stereotype that blondes are less intelligent is unsupported by scientific evidence.
Your daughter is 3 years old and she already knows how to read? She's so smart!
The word clever has the connotation of being smart in a creative way. If somebody is able to find an unusual and innovative solution to a problem, which nobody else imagined, we would describe the person as clever. A clever person can be good or bad:
A person who creates an interesting new method of reusing recycled material is clever.
A thief who invents a creative way to break into a bank and rob it is also clever.
Drew Barrymore is looking in the pink of her health in this picture. Her figure is nothing short of an hourglass, her legs are nicely toned, her arms are just as toned too and her thighs are without a trace ugly cellulite. Not to mention the fact that her stomach is absolutely flat and her skin is glowing. And all this because Barrymore regularly does yoga. No fad diets or extreme exercises for Barrymore. It is only yoga that the lady swears by to keep herself fit. In this picture too, Barrymore can be seen carrying a yoga mat and a bottle of water ample proof that for Barrymore yoga is the secret to fitness.