Grey-brown (3)
I believe the answer is:
dun
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">grey</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">brown</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that dun is a type of light brown)</span><br/ ><br/ ></span>
(Other definitions for dun that I've seen before include "Dull brownish-grey colour" , "Brownish grey horse" , "Dingy brown" , "press for money" , "nag, for payment" .)