Henna, e.g (3)
I believe the answer is:
dye
'henna eg' is the definition.
(henna is a kind of dye)
This is all the clue.
(Other definitions for dye that I've seen before include "Colorant" , "Colouring material" , "Colour (fabrics)" , "Colouring liquid" , "Colourant" .)