Sicily's highest peak (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sicily's highest peak</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for etna that I've seen before include "Heating vessel" , "source of fumes?" , "Italian smoker" , "burning mountain" , "Sicilian volcano" .)