Hastens to provide a variety of shades (6)
I believe the answer is:
dashes
'hastens' is the definition.
(dashing is a kind of hastening)
'a variety of shades' is the wordplay.
'a variety of' indicates anagramming the letters.
'shades' anagrammed gives 'DASHES'.
'to provide' is the link.
(Other definitions for dashes that I've seen before include "Makes a quick run" , "Darts" , "Quick run or sudden rush" , "Sprints, runs fast" , "Strokes" .)