Teasing unpleasantly (8)
I believe the answer is:
taunting
'teasing unpleasantly' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for taunting that I've seen before include "Attuning to jeering mode" , "Jeering, mocking" , "Teasing unpleasantly" , "Baiting" .)