Concern about play's fiddle music (7)
I believe the answer is:
calypso
'music' is the definition.
(I've seen this before)
'concern about play's fiddle' is the wordplay.
'concern' becomes 'co' (short for company - concern can mean a business).
'about' means one lot of letters goes inside another.
'fiddle' is an anagram indicator.
'plays' is an anagram of 'alyps'.
'co' enclosing 'alyps' is 'CALYPSO'.
(Other definitions for calypso that I've seen before include "West Indian music style" , "island song" , "Topical West Indian song - orchid - sea nymph" , "Improvised song of the Caribbean" , "Satirical West Indian song and dance" .)