Carrying a gun did make it bulge (7)
I believe the answer is:
distend
'bulge' is the definition.
(I've seen this before)
'carrying a gun did make' is the wordplay.
'carrying' indicates putting letters inside.
'a gun' becomes 'sten' (British sub-machine gun).
'did make' becomes 'did' ('do' can be a synonym of 'make').
'sten' inserted into 'did' is 'DISTEND'.
'it' is the link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for distend that I've seen before include "Swell by pressure from within" , "Bloat" , "balloon" , "Swell with internal pressure" , "blow up" .)