Ironic (3)
I believe the answer is:
wry
'ironic' is the definition.
(wry can mean ironic or humorous)
This is all the clue.
(Other definitions for wry that I've seen before include "Of facial expression, mocking or twisted" , "Of humour, dry and mocking" , "Drily humorous" , "Mockingly humorous" , "Twisted; sardonic" .)