Antarctic volcano (6)
I believe the answer is:
erebus
'antarctic volcano' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for erebus that I've seen before include "The abode of the dead" , "Volcanic mountain in Antarctica" , "God of darkness - cavern on the way to Hades - active volcano in Antarctica" , "In place of darkness" , "Greek god of darkness, son of Chaos" .)