Dubbing for film musical (6)
I believe the answer is:
grease
This clue is a double definition.
'dubbing' is the first definition.
(dub can mean to smear with grease)
'film musical' is the second definition.
(Grease is a 1978 film musical)
'for' is the link.
(Other definitions for grease that I've seen before include "Musical - lubricant" , "Fully aware, astonished" , "Musical starring John Travolta and Olivia Newton-John" , "Lubricate - musical" , "Fatty lubricant" .)