Offence exploits openings in person? (7)
I believe the answer is:
sinuses
'openings in person?' is the definition.
(sinuses are cavities or openings in the body)
'offence exploits' is the wordplay.
'offence' becomes 'sin' (I've seen this before).
'exploits' becomes 'uses' (use is a kind of exploit).
'sin'+'uses'='SINUSES'
(Other definitions for sinuses that I've seen before include "Empty spaces" , "Top spaces" , "Cavities in skull connecting with nostrils" , "holes in the head" .)