Colours ultimately faded of course (4)
I believe the answer is:
dyes
'colours' is the definition.
(dyeing is a kind of colouring)
'ultimately faded of course' is the wordplay.
'ultimately' indicates one should take the final letters.
'of course' becomes 'yes' (I've seen this before).
The final letter of 'faded' is 'd'.
'd'+'yes'='DYES'
(Other definitions for dyes that I've seen before include "Colouring materials" , "Stains" , "Colour" , "Colours (fabric)" , "Substances for staining or colouring" .)