Greek underworld (5)
I believe the answer is:
hades
'greek underworld' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for hades that I've seen before include "Greek underworld with spirits of the dead" , "Home of the souls of the dead" , "In Greek myth, the Underworld" , "Infernal situation" , "It's hell in the Greek shade" .)