A piece of music (3)
I believe the answer is:
bar
'a piece of music' is the definition.
'a piece of music' is the wordplay.
I cannot quite see how this works, but
'a' is within the answer.
'piece' could be 'r' (abbreviation for Rook) and 'r' is located in the answer.
'music' could be 'b' and 'b' is present in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for bar that I've seen before include "Saloon" , "Shut out" , "Sandbank; pub counter" , "Exclude; sandbank" , "sovereign" .)