Zebra marking (6)
I believe the answer is:
stripe
'zebra marking' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for stripe that I've seen before include "Band of colour, maybe of rank" , "Streak" , "Priest (anag)" , "promotion, maybe" , "Chevron on a uniform to denote military rank" .)