An active volcano in Sicily (4)
I believe the answer is:
etna
'an active volcano in sicily' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for etna that I've seen before include "hole in the crust" , "Natural hazard" , "burning mountain" , "Neat class of volcano in Sicily" , "Volcano in Sicily, quite neat" .)