Relating to colour (9)
I believe the answer is:
chromatic
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">relating to colour</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know this)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for chromatic that I've seen before include "With use of colour" , "in colours" , "Trim coach (anag.)" , "colourful?" .)