Ball that's gold and black (3)
I believe the answer is:
orb
'ball' is the definition.
('orb' can be a synonym of 'ball')
'gold and black' is the wordplay.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'and' means one lot of letters go next to another.
'black' becomes 'b' (as in pencil classifications).
'or'+'b'='ORB'
'that's' acts as a link.
(Other definitions for orb that I've seen before include "Ornamental globe" , "ball with cross" , "A poetic eye, bro" , "Poetically eye" , "Jewelled ornament" .)