Quiz polished off with a will? (7)
I believe the answer is:
testate
'with a will?' is the definition.
(I've seen this before)
'quiz polished off' is the wordplay.
'quiz' becomes 'test' ('test' can be a synonym of 'quiz').
'polished off' becomes 'ate' (I've seen this in other clues).
'test'+'ate'='TESTATE'
(Other definitions for testate that I've seen before include "Leaving a will" , "With a legally valid will" , "State of having made a will" , "Having left a legacy" , "Having made a valid will" .)