Mocking irony (7)
I believe the answer is:
sarcasm
'mocking irony' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for sarcasm that I've seen before include "Language expressing scorn or contempt" , "Show of ironic contempt" , "Gibe" , "insulting language" , "The use of irony to convey contempt" .)