Light mauvish-crimson (7)
I believe the answer is:
magenta
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">light mauvish-crimson</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for magenta that I've seen before include "Name tag (anag) - colour" , "Bright purplish red or magnate" , "Bright purplish-red" , "Reddish purple" , "Deep purplish red" .)