A black queen can be superior (6)
I believe the answer is:
abbess
'be superior' is the definition.
(I've seen this before)
'a black queen' is the wordplay.
'black' becomes 'b' (as in pencil classifications).
'queen' becomes 'bess' (I've seen this before).
'a'+'b'+'bess'='ABBESS'
'can' acts as a link.
(Other definitions for abbess that I've seen before include "Superior of group of nuns" , "Head of group of nuns" , "Nuns' leader" , "Female superior" , "superior to her sisters!" .)