Talk of quiet baby's toy (7)
I believe the answer is:
prattle
'talk' is the definition.
(prattle is a kind of talk)
'quiet baby's toy' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano').
'baby's toy' becomes 'rattle' (I've seen this before).
'p'+'rattle'='PRATTLE'
'of' acts as a link.
(Other definitions for prattle that I've seen before include "Chatter inconsequentially, natter" , "Talk emptily" , "Inconsequential chatter" , "Talk childishly" , "Idle talk" .)