A piano with a bell-like sound, has charm (6)
I believe the answer is:
'charm' is the definition.
(I know that charm is a more specific form of the action appeal)
'a piano with a bell-like sound' is the wordplay.
'piano' becomes 'p' (musical abbreviation).
'with' means one lot of letters go next to another.
'a bell-like sound' becomes 'peal' (I can't explain this - if you can you should give a lot more credence to this answer).
'has' acts as a link.
Can you help me to learn more?
(Other definitions for appeal that I've seen before include "Beg" , "Take case to higher court to challenge verdict" , "Earnest or urgent request" , "Ask earnestly" , "Petition or attraction" .)