Volcanic discharge (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">volcanic discharge</span>' is the definition.<br/ ><span class="explanation-format__explanation">(lava is released in a volcanic eruption)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for lava that I've seen before include "Stuff heatedly hurled out" , "It flows from volcano" , "Volcanic outpouring" , "Molten volcanic rock" , "Volcanic spillage" .)