Just the sort of gun for a soldier? (5)

I believe the answer is:

tommy

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'for a soldier?' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

(Other definitions for tommy that I've seen before include "Private soldier (slang)" , "British private soldier (colloq.)" , "British soldier (informal)" , "Private in the Army - kind of gun" , "Doubtful apostle could be so familiar" .)

I've seen this clue in the Evening Standard.

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