Complete filming of "The Sound of Music" (4)
I believe the answer is:
wrap
'complete filming' is the definition.
(I've seen this in another clue)
'sound of music' is the wordplay.
'sound of' indicates a 'sounds like' (homophone) clue.
'music' becomes 'rap' (musical genre).
'rap' sounds like 'WRAP'.
'of the' is the link.
(Other definitions for wrap that I've seen before include "Pack in paper; shawl" , "package" , "Finish filming" , "End of a filming session" , "Bathrobe" .)