Whiteboard accessory (6)
I believe the answer is:
eraser
'whiteboard accessory' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eraser that I've seen before include "A schoolboy's rubber" , "What a poor artist needs" , "Writing remover" , "(Pencil, ink) rubber" , "Obliterator" .)