Mock, scoff at (6)
I believe the answer is:
deride
I believe this clue is a double definition.
'mock' is the first definition.
(deriding is a kind of mocking)
'scoff at' is the second definition.
(I've seen this in another clue)
(Other definitions for deride that I've seen before include "Speak of with contempt" , "Knock" , "Jeer, belittle" , "Mock, scorn" , "Ridicule, laugh at" .)