Vulcan's Chimney (4)
I believe the answer is:
etna
'vulcan's chimney' 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 "Active European volcano" , "Threatening mountain" , "Volcano in Italy" , "hotly-tipped runner" , "Volcano; reverse of stake" .)