Only men party with sinister-looking guns (4)
I believe the answer is:
stag
'only men party' is the definition.
(as in a stag night)
'sinister-looking guns' is the wordplay.
'sinister-looking' shows that the letters should be reversed in order (text right-to-left - sinister is left in Latin).
'guns' becomes 'gats' (gat is a kind of gun).
'gats' in reverse letter order is 'STAG'.
'with' is the link.
(Other definitions for stag that I've seen before include "American party" , "Stockmarket operator gambling on a quick profit" , "Unaccompanied man at party" , "Antlered beast" , "involving men" .)