Colouring pencil (6)
I believe the answer is:
crayon
'colouring pencil' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for crayon that I've seen before include "Drawing implement" , "Coloured rod" , "Stick to colour" , "Stick of coloured wax for drawing (6)" , "One colours with this" .)