The spirit of darkness (5)
I believe the answer is:
shade
This clue is a double definition.
'the spirit' is the first definition.
(thesaurus)
'darkness' is the second definition.
(shade is a kind of darkness)
'of' is the link.
(Other definitions for shade that I've seen before include "Hue" , "Colour; lamp cover" , "Relative darkness" , "Colour; slight amount" , "remains" .)