Playing incomplete movie title theme (9)
I believe the answer is:
leitmotiv
'theme' is the definition.
(I've seen this before)
'playing incomplete movie title' is the wordplay.
'playing' indicates anagramming the letters.
'incomplete' means to remove the last letter.
'movie'+'title'='movietitle'
'movietitle' with its final letter taken away is 'movietitl'.
'movietitl' anagrammed gives 'LEITMOTIV'.
(Other definitions for leitmotiv that I've seen before include "Musical theme" , "Limit vote (anag.)" , "Recurring literary theme" , "recurrent idea" , "repetitive theme" .)