Coloured part of eye (4)
I believe the answer is:
iris
'coloured part of eye' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for iris that I've seen before include "Ms Murdoch" , "Pupil is at the centre of this" , "Plant - part of the eye" , "Bright flower or eye part" , "may open up in camera" .)