Blush, flush (6)
I believe the answer is:
redden
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">blush</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">flush</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for redden that I've seen before include "Blush or become flushed" , "Evaluate the nature of (something)" , "Reveal embarrassment in colourful way" , "Give visible sign of embarrassment" , "Blush, colour accordingly" .)