The Greek underworld (5)
I believe the answer is:
hades
'the greek underworld' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for hades that I've seen before include "Classic hell in the shade" , "Infernal situation" , "In Greek myth, the Underworld" , "Mythological abode of the dead" , "A place of some darkness" .)