Changing colour and passing away audibly (6)
I believe the answer is:
dyeing
'changing colour' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for dyeing that I've seen before include "Changing colour - sounds terminal" , "Browning, perhaps" , "Changing colour by dipping in liquid" , "colouring yarns" , "Giving a new colour to" .)