Soldier's name for a gun (5)
I believe the answer is:
tommy
'soldier's' is the definition.
(I have seen 'British soldier' mean 'tommy' so perhaps 'soldier' could also mean 'tommy')
'name for a gun' is the wordplay.
'name' becomes 'Tom'.
'for' is a charade indicator (letters next to each other).
'a gun' becomes 'my' (I can't justify this - if you can you should believe this answer much more).
'tom'+'my'='TOMMY'
Can you help me to learn more?
(Other definitions for tommy that I've seen before include "Doubtful apostle could be so familiar" , "Private soldier (slang)" , "British private soldier (colloq.)" , "Private in the Army - kind of gun" , "British soldier (informal)" .)