Ace duet spoiled in school (7)
I believe the answer is:
educate
'school' is the definition.
(I know that school can be written as educate)
'ace duet spoiled' is the wordplay.
'spoiled' indicates anagramming the letters.
'ace'+'duet'='aceduet'
'aceduet' anagrammed gives 'EDUCATE'.
'in' acts as a link.
(Other definitions for educate that I've seen before include "Teach - instruct" , "Enlighten" , "Bring up" , "Give instruction to" , "teaching style" .)