Twelve minus zero, bonus puzzle (7)
I believe the answer is:
nonplus
'puzzle' is the definition.
(I know that puzzle can be written as nonplus)
'twelve minus zero bonus' is the wordplay.
'twelve' becomes 'noon' (twelve noon).
'minus' suggests deleting specific letters.
'zero' becomes 'O' (O resembles 0).
'bonus' becomes 'plus' (I've seen this before).
'noon' with 'o' taken away is 'non'.
'non'+'plus'='NONPLUS'
(Other definitions for nonplus that I've seen before include "Baffle" , "nothing if not negative?" , "Disconcert, confound" , "Put at a loss; confuse" , "Throw into confusion" .)