A gun hidden in peach trifle (9)
I believe the answer is:
bagatelle
'trifle' is the definition.
(I've seen this before)
'a gun hidden in peach' is the wordplay.
'gun' becomes 'gat' (gat is a kind of gun).
'hidden in' indicates putting letters inside.
'peach' becomes 'belle' (I can't justify this - if you can you should believe this answer much more).
'a'+'gat'='agat'
'agat' put within 'belle' is 'BAGATELLE'.
Can you help me to learn more?
(Other definitions for bagatelle that I've seen before include "Musical item" , "Something trivial" , "Unimportant thing" , "drop in the ocean!" , "Board game - trifle" .)