Etna's outpouring (4)
I believe the answer is:
lava
'etna's outpouring' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lava that I've seen before include "Discharge from volcano" , "Immature insect form" , "Emanation from volcano" , "Stuff heatedly hurled out" , "Volcanic outpouring" .)