Small bagpipe group has broken making no sound (7)
I believe the answer is:
musette
'small bagpipe' is the definition.
'musette' can be an answer for 'bagpipe' (musette is a kind of bagpipe). I am not certain of the 'small' bit.
'group has broken making no sound' is the wordplay.
'group' becomes 'set' (both can mean a collection).
'has broken' indicates putting letters inside (inserted letters break in).
'making no sound' becomes 'mute' (I can't explain this - if you can you should give a lot more credence to this answer).
'set' put within 'mute' is 'MUSETTE'.
Can you help me to learn more?
(Other definitions for musette that I've seen before include "dance" , "Old wind instrument" , "bagpipe" , "Bag" , "doughboy's kitbag" .)