Clever, not needing book to be correct (5)
I believe the answer is:
right
'be correct' is the definition.
(synonyms)
'clever not needing book' is the wordplay.
'clever' becomes 'bright' (bright can mean clever or gifted).
'not needing' indicates named letters should be taken away.
'book' becomes 'b' (abbreviation for book).
'bright' with 'b' removed is 'RIGHT'.
'to' is the link.
(Other definitions for right that I've seen before include "Correct - starboard" , "Properly" , "Valid" , "A person is entitled to it" , "Quite proper" .)