Remain black and sticky (5)
I believe the answer is:
tarry
This clue is a triple definition!
'remain' is the first definition.
(I've seen this in another clue)
'black' is the second definition.
(thesaurus)
'and' acts as a link.
'sticky' is the third definition.
(I've seen this before)
(Other definitions for tarry that I've seen before include "Stay longer than intended" , "Hang around" , "covered with dark liquid" , "perhaps not to split" , "Like fresh road surface" .)