Scornfully mocking (8)
I believe the answer is:
sardonic
'scornfully mocking' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sardonic that I've seen before include "Scornfully derisive" , "Dry, cynically mocking" , "Mocking or scornful" , "Scornfully mocking" , "Tart" .)