Quilt colour that is turning blue (9)
I believe the answer is:
eiderdown
'quilt' is the definition.
(eiderdown is a kind of quilt)
'colour that is turning blue' is the wordplay.
'colour' becomes 'red' (red is a kind of colour).
'that is' becomes 'ie' (abbreviation for id est, 'that is' in Latin).
'turning' shows that the letters should be reversed in order.
'blue' becomes 'down' (both can mean sad).
'red'+'ie'='redie'
'redie' reversed gives 'eider'.
'eider'+'down'='EIDERDOWN'
(Other definitions for eiderdown that I've seen before include "cover when retired" , "Soft quilt filled with duck feathers" , "what ducks have to offer us" , "Feather quilt" , "I wondered about this warm bed covering" .)