Scoff, mock (4)
I believe the answer is:
jeer
This clue is a double definition.
'scoff' is the first definition.
(both can mean to mock)
'mock' is the second definition.
(I've seen this in another clue)
(Other definitions for jeer that I've seen before include "Ridicule noisily" , "Boo" , "Taunt" , "Scoff, deride, mock" , "Laugh at with derision" .)