A flower that's yellow and black, say, is given a prize (9)
I believe the answer is:
buttercup
'a flower that's yellow' is the definition.
'black say is given a prize' is the wordplay.
'black' becomes 'b' (as in pencil classifications).
'say' becomes 'utter' (I've seen this before).
'is given' is a charade indicator (letters next to each other).
'a prize' becomes 'cup' (cup is a kind of prize).
'b'+'utter'+'cup'='BUTTERCUP'
'and' is the link.
(Other definitions for buttercup that I've seen before include "Goldilocks, possibly" , "Yellow-flowered grassland plant" , "Rich yellow wild flower" , "Meadow flower poisonous to cattle" , "growth in the field" .)