Colouring agent (3)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">colouring agent</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 dye that I've seen before include "Pigment" , "Colouring; sounds like fade" , "Colourant" , "Colouring liquid" , "Staining material" .)
(Other definitions for pigment that I've seen before include "Colour or dye" , "Colouring material" , "Colourful substance" , "become imbued" , "Colouring matter" .)