Slight colouring (5)
I believe the answer is:
tinge
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">slight colouring</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 tinge that I've seen before include "A shade or a nuance" , "Slight tint" , "Colour slightly; trace" , "Touch (of colour?)" , "Slight but perceptible amount" .)