Musical chap (6)
I believe the answer is:
oliver
This clue is a double definition.
'musical' is the first definition.
(musical based on Oliver Twist)
'chap' is the second definition.
(Other definitions for oliver that I've seen before include "Chef" , "Orphan recruited by criminal gang" , "The boy who wanted more" , "Dickensian musical" , "Musical based on the story of Dickens boy" .)