Black Prince, say, is reported as something black (6)
I believe the answer is:
knight
'black prince say' is the definition.
'reported as something black' is the wordplay.
'reported as' shows a homophone (sound like).
'something black' becomes 'night'.
'night' sounds like 'KNIGHT'.
'is' acts as a link.
(Other definitions for knight that I've seen before include "Man on board" , "He's a Sir in the UK" , "in quest for a mate" , "Jumping chess piece" , "Chevalier" .)