Of elves (5)
I believe the answer is:
elfin
'of elves' is the definition.
(I know this)
This is all the clue.
(Other definitions for elfin that I've seen before include "Small; impish" , "Resembling one of the little people" , "Small and fragile" , "Pixie-like" , "Small, delicate and mischievous-looking" .)