Put firearm in corner, perhaps (3,5)
I believe the answer is:
set piece
'corner perhaps' is the definition.
(I've seen this before)
'put firearm' is the wordplay.
'put' becomes 'set' (setting is a kind of putting).
'firearm' becomes 'piece' ('piece' can be a synonym of 'firearm').
'set'+'piece'='SET PIECE'
'in' is the link.
(Other definitions for set piece that I've seen before include "corner, say" , "Piece of writing arranged for maximum effect" , "oft-rehearsed play" , "Carefully structured and practised speech - see pi, etc (anag)" , "Standard manoeuvre" .)