Coloured wax pencil (6)
I believe the answer is:
crayon
'coloured wax 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" , "Waxy pencil" , "Wax colouring stick" , "Coloured wax pencil" , "Pencil of chalk or wax" .)