Pigment made from clay and iron oxide (5)
I believe the answer is:
ochre
'pigment made from clay and iron oxide' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for ochre that I've seen before include "Money" , "Yellow-orange hue" , "Yellow-red mineral from iron oxide used as pigment" , "Light yellow-brown colour" , "natural colouring" .)