Red food dye (9)
I believe the answer is:
cochineal
'red food dye' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cochineal that I've seen before include "Red food dye (from beetles)" , "Red colour" , "Scarlet food dye" , "Scarlet dye - in a cloche (anag)" , "Red food colouring" .)