Man carrying weapon in jacket perhaps (7)
I believe the answer is:
garment
'jacket perhaps' is the definition.
(jacket is a kind of garment)
'man carrying weapon' is the wordplay.
'man' becomes 'gent' (gent is a kind of man).
'carrying' means one lot of letters goes inside another.
'weapon' becomes 'arm' (synonyms).
'gent' going around 'arm' is 'GARMENT'.
'in' is the link.
(Other definitions for garment that I've seen before include "Maybe a jacket" , "Raiment" , "coat maybe" , "Grant me (anag.)" , "Vestment" .)