A volcanic mountain (4)
I believe the answer is:
etna
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a volcanic mountain</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 "it may produce steam and ash" , "Natural hazard" , "Neat class of volcano in Sicily" , "Sicilian hothead?" , "Long-term smoker" .)