Small and mischievous (5)
I believe the answer is:
elfin
'small and mischievous' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for elfin that I've seen before include "Delicately framed" , "Small, mischievous and charming" , "puckish" , "Like a mischievous fairy" , "Dainty" .)