Yellow-brown pigment (6)
I believe the answer is:
sienna
'yellow-brown pigment' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sienna that I've seen before include "yellowy-brown" , "colouring" , "Raw -; burnt -" , "Browny-yellow pigment" , "-- Sauce; -- toast" .)