Musical film shot in Oz (7)
I believe the answer is:
amadeus
'musical film' is the definition.
(1984 Mozart biopic)
'shot in oz' is the wordplay.
'shot' becomes 'made' (to shoot a film is to make it).
'in' is an insertion indicator.
'oz' becomes 'aus' (both can mean Australia).
'made' put within 'aus' is 'AMADEUS'.
(Other definitions for amadeus that I've seen before include "Film/play life of Mozart" , "See 7" , "Shaffer play; Forman 1984 film" , "Mozart's middle name" , "Mozart's second name" .)