Deep red (7)
I believe the answer is:
crimson
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">deep red</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for crimson that I've seen before include "Become red-faced" , "Blood-red" , "Shade of red" , "Rich deep red" , "Blush" .)