Tarnish; dye (5)
I believe the answer is:
stain
I believe this is a double definition.
'tarnish' is the first definition.
(I know that tarnish can be written as stain)
'dye' is the second definition.
(I know that stain is a type of dye)
(Other definitions for stain that I've seen before include "Mark with colour, dirt" , "Discoloration" , "Blot" , "Discolouration" , "Discolouring mark" .)