Shaker to accompany piano? Nonsense (7)
I believe the answer is:
prattle
'nonsense' is the definition.
(thesaurus)
'shaker to accompany piano?' is the wordplay.
I cannot really understand how this works, but
'piano?' could be 'p' and 'p' is found in the answer.
The remaining letters 'rattle' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for prattle that I've seen before include "Idle chatter" , "Idle talk" , "Talk emptily" , "Childish talk" , "Be vapidly garrulous" .)