Discharged while holding gun to bulge (7)
I believe the answer is:
distend
'bulge' is the definition.
(I've seen this before)
'discharged while holding gun' is the wordplay.
'discharged while' becomes 'did' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'holding' indicates putting letters inside.
'gun' becomes 'sten' (British sub-machine gun).
'did' enclosing 'sten' is 'DISTEND'.
'to' is the link.
Can you help me to learn more?
(Other definitions for distend that I've seen before include "Expand, inflate" , "Make you bulge" , "blow up" , "balloon" , "Increase" .)