Round left in quiz (5)
I believe the answer is:
plump
'round' is the definition.
(I've seen this before)
'left in quiz' is the wordplay.
'left' becomes 'l' (common abbreviation).
'in' is an insertion indicator.
'quiz' becomes 'pump' (both can mean to interrogate).
'l' put within 'pump' is 'PLUMP'.
(Other definitions for plump that I've seen before include "Fat - set down unceremoniously" , "Chubby, rounded" , "Slightly fat" , "Buxom, chubby" , "Rather fat" .)