Is a fool to tease (4)
I believe the answer is:
twit
'to tease' is the definition.
(synonyms)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for twit that I've seen before include "dunce" , "Ninny" , "Silly fool" , "Idiot; tease" , "Bait - fool" .)