Mope (4)
I believe the answer is:
sulk
'mope' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sulk that I've seen before include "Fit of bad temper" , "Be in a huff" , "Crime involving fire" , "Pout" , "Mood of sullen aloofness" .)