What may be offensive clothes get wrapped in foil, perhaps (9)
I believe the answer is:
swearword
'what may be offensive' is the definition.
'clothes get wrapped in foil perhaps' is the wordplay.
'clothes' becomes 'wear' (synonyms).
'get wrapped in' indicates putting letters inside.
'foil perhaps' becomes 'sword' (foil is a kind of sword).
'wear' put within 'sword' is 'SWEARWORD'.
(Other definitions for swearword that I've seen before include "blast perhaps" , "profanity" , "Oath" .)