Ivory's counterpart (5)
I believe the answer is:
ebony
'ivory's counterpart' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ebony that I've seen before include "Very dark brown" , "Hard wood used for black piano keys and in cabinetwork" , "Material for key" , "'Hard, dark wood (5)'" , "Black hardwood" .)