Initially horror and despair engulf sufferers here (5)
I believe the answer is:
hades
'here' is the definition.
(thesaurus)
'initially horror and despair engulf sufferers' is the wordplay.
'initially' says to take the initial letters.
The initial letters of 'horror and despair engulf sufferers' is 'HADES'.
(Other definitions for hades that I've seen before include "A place of some darkness" , "Greek underworld with spirits of the dead" , "Infernal situation" , "Classic hell in the shade" , "Pluto" .)