Scandalous to give Oscar to dumb final part of film (7)
I believe the answer is:
obscene
'scandalous' is the definition.
'oscar to dumb final part of film' is the wordplay.
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'final' indicates one should take the final letters.
'part of film' becomes 'scene' ('scene' is part of 'film').
The last letter of 'dumb' is 'b'.
'o'+'b'+'scene'='OBSCENE'
'to give' is the link.
(Other definitions for obscene that I've seen before include "Offensive - indecent" , "off colour?" , "Bawdy" , "offending sensibilities?" , "Morally offensive, disgusting" .)