Tarnish, sully (5)
I believe the answer is:
stain
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">tarnish</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">sully</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for stain that I've seen before include "Discolouring mark" , "Dirty mark; dye" , "Stigma" , "Tarnish" , "Mark with colour, dirt" .)