Offbeat, unconventional (6)
I believe the answer is:
quirky
I believe this clue is a double definition.
'offbeat' is the first definition.
(synonyms)
'unconventional' is the second definition.
(similar in meaning)
(Other definitions for quirky that I've seen before include "Peculiar in behaviour" , "'Kinky, off-beat (6)'" , "Idiosyncratic" .)