Wrong — idol repeats core of a piece of music (5)
I believe the answer is:
rondo
'music' is the definition.
(rondo is a kind of music)
'wrong idol repeats core of a piece' is the wordplay.
'wrong idol repeats' becomes 'ron' (I am not sure about this - if you are sure you should believe this answer much more).
'core of' means to remove the middle letters (I've seen 'cored' mean this).
'a piece' becomes 'duo' (duo is a kind of piece).
'duo' with its middle removed is 'do'.
'ron'+'do'='RONDO'
'of' is the link.
Can you help me to learn more?
(Other definitions for rondo that I've seen before include "Piece in the form of a sonata's last movement, say" , "Music form with repeating theme" , "Musical work" , "has repetitive theme" , "Musical composition with a recurring theme" .)