Vulcan's Chimney (4)
I believe the answer is:
etna
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">vulcan's chimney</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(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" .)