Evil applications of holes in the head? (7)
I believe the answer is:
sinuses
'holes in the head?' is the definition.
(I've seen this in another clue)
'evil applications' is the wordplay.
'evil' becomes 'sin' (synonyms).
'applications' becomes 'uses' (I've seen this in another clue).
'sin'+'uses'='SINUSES'
'of' acts as a link.
(Other definitions for sinuses that I've seen before include "Empty spaces" , "Cavities in skull connecting with nostrils" , "Top spaces" , "holes in the head" .)