Quiet for a gun they say (5)
I believe the answer is:
peace
'quiet' is the definition.
(thesaurus)
'a gun they say' is the wordplay.
'a gun' becomes 'piece' (piece is a kind of gun).
'they say' shows a homophone (sound like).
'piece' sounds like 'PEACE'.
'for' is the link.
(Other definitions for peace that I've seen before include "See 1" , "Calm, tranquility" , "Freedom from disturbance, tranquillity" , "A Christmas wish" , "Calmness" .)