Light listening, mostly piano music (4)
I believe the answer is:
pops
'light listening mostly piano music' is the definition.
I can't tell whether this definition defines the answer.
'listening mostly piano music' is the wordplay.
'listening' becomes 'po' (I am not sure about this - if you are sure you should believe this answer much more).
'mostly' means to remove the last letter (most but not all of the word).
'piano' becomes 'p' (musical abbreviation).
'music' becomes 'so' (as in do re mi fa so la ti).
'p'+'so'='pso'
'pso' with its final letter taken off is 'ps'.
'po'+'ps'='POPS'
Can you help me to learn more?
(Other definitions for pops that I've seen before include "Dads or sweet drinks" , "light classical pieces" , "Bursts noisily" , "Explodes, bursts" .)