Worry about receptacle for gun (7)
I believe the answer is:
carbine
'gun' is the definition.
(carbine is a kind of gun)
'worry about receptacle' is the wordplay.
'worry' becomes 'care' (I've seen this before).
'about' indicates putting letters inside.
'receptacle' becomes 'bin' (I've seen this before).
'care' going around 'bin' is 'CARBINE'.
'for' is the link.
(Other definitions for carbine that I've seen before include "A short light automatic rifle" , "Light automatic rifle -- nice bra (anag)" .)