Swindler pinching girl’s large gun (6)
I believe the answer is:
cannon
'large gun' is the definition.
(I've seen this before)
'swindler pinching girl's' is the wordplay.
'swindler' becomes 'con' (I've seen this in other clues).
'pinching' is an insertion indicator (taking inside).
'girl' becomes 'ann' (woman's name).
'con' placed around 'ann' is 'CANNON'.
(Other definitions for cannon that I've seen before include "Field gun" , "Billiard shot or large gun" , "Billiard shot in which player's ball hits the two others" , "shot playing billiards" , "mortar" .)