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.
Plan for the Valentines Day Party weeks in advance.
Select the theme for the party and accordingly plan your decorations.
Send invitations two weeks in advance and inform guests about dress code if there is any.
Announce a prize for the most innovatively dressed person to inspire your guests.
Plan the menu and book the caterer in time to avoid last minute hassles.
Delegate the work of decoration, gifts etc to friends or family members so that work progresses smoothly and nobody feels burdened.