Quietly mentioned being favoured (9)
I believe the answer is:
'favoured' is the definition.
('prefer' can be a synonym of 'favour')
'quietly mentioned being' is the wordplay.
I cannot really understand how this works, but
'quietly' could be 'p' (p for piano and quiet) and 'p' is found within the answer.
'being' could be 'red' (red is a kind of being) and 'red' is present in the answer.
The remaining letters 'refer' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for preferred that I've seen before include "Chose before others" , "Liked better" , "choice" , "Was partial to" , "singled out" .)