Tongue-in-cheek (6)
I believe the answer is:
ironic
'tongue-in-cheek' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ironic that I've seen before include "Causing wry amusement through an unexpected outcome" , "Double-edged" , "A form of sarcasm, may sound perverse" , "Wryly amusing" , "(Of a happening) having significance not perceived at the time" .)