Soft toy rabbit (7)
I believe the answer is:
prattle
'rabbit' is the definition.
(both can mean to talk excessively)
'soft toy' is the wordplay.
'soft' becomes 'p' (musical abbreviation for 'piano').
'toy' becomes 'rattle' (I've seen this before).
'p'+'rattle'='PRATTLE'
(Other definitions for prattle that I've seen before include "Chat inconsequentially" , "Inconsequential chatter" , "waffle" , "Chatter inanely" , "Talk childishly" .)