Mischievous kid (3)
I believe the answer is:
imp
'mischievous kid' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for imp that I've seen before include "Sprite; add feathers to" , "Small devil or sprite" , "Small mischievous spirit" , "Small mischievous sprite" , "Elf" .)