Quietly put down toy (4)
I believe the answer is:
play
'toy' is the definition.
('play' can be a synonym of 'toy')
'quietly put down' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'put down' becomes 'lay' ('lay' can be a synonym of 'put down').
'p'+'lay'='PLAY'
(Other definitions for play that I've seen before include "Amuse oneself - drama" , "Make sport" , "Scope - entertainment" , "Slack - performance" , "Stage work" .)