Audibly fades to reveal colours (4)
I believe the answer is:
dyes
'colours' is the definition.
(dyeing is a kind of colouring)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for dyes that I've seen before include "Many a pigment" , "Colours (fabric)" , "Substances for staining or colouring" , "Colour" , "Stains" .)