There are fewer nouns than adjectives for someone who is smart, intelligent, bright, brilliant, or wise.
Some terms are genius, ace, intellect (intellectual), savant, academic, or scholar.
Colloquial terms include brain, egghead, Einstein, thinker, or whiz.
One word is diencephalon.
mane smart one
A 6-letter word beginning with 'a' that means smart is astute.
Intelligent
Precocious
The is one syllable in the word, smart.
Astute is a word that means smart.
The word you are looking for is "clever."
I think it means "Smart"
understanding
pie
Enlightened