Mock director with dreadful revolting movie's finale (6)
I believe the answer is:
deride
'mock' is the definition.
(deriding is a kind of mocking)
'director with dreadful revolting movie's finale' is the wordplay.
'director' becomes 'd' (abbreviation eg in film reviews).
'with' is a charade indicator (letters next to each other).
'dreadful' becomes 'dire' (synonyms).
'revolting' is a reversal indicator.
'finale' says to take the final letters.
The last letter of 'movie' is 'e'.
'dire' in reverse letter order is 'erid'.
'd'+'erid'+'e'='DERIDE'
(Other definitions for deride that I've seen before include "Speak of with contempt" , "'Mock, sneer at (6)'" , "Ridicule, laugh at" , "Mock and jeer" , "Test performance" .)