Artificially coloured (4)
I believe the answer is:
dyed
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">artificially coloured</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for dyed that I've seen before include "Artificially coloured" , "Changed to a new colour" , "(Of fabric) coloured" , "Imbued with artificual colour" , "Cloth is often" .)