Erupting mountain (7)
I believe the answer is:
volcano
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">erupting mountain</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for volcano that I've seen before include "Erupting hole in the earth's crust" , "source of vents" , "kind of mountain" , "Etna, for example" , "Exploding mountain" .)