Amusingly unconventional (4)
I believe the answer is:
zany
'amusingly unconventional' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for zany that I've seen before include "Madcap, like a clown" , "Left-field - foolish" , "Amusingly odd" , "Bizarrely comic" , "Amusingly idiosyncratic" .)