Santa's helper (3)
I believe the answer is:
elf
'santa's helper' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for elf that I've seen before include "Mischievous creature" , "Robin Goodfellow?" , "Diminutive folklore creature" , "Hobgoblin" , "Malignant fairy" .)