Cave-dwelling dwarf (5)
I believe the answer is:
troll
'cave-dwelling dwarf' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for troll that I've seen before include "who's stirring on-line" , "supposedly lives in a cave" , "Fish; goblin" , "Dwarfish creature" , "Online pest" .)