In favour of drink soprano rejects (8)
I believe the answer is:
forsakes
'rejects' is the definition.
(to reject is to abandon or forsake)
'in favour of drink soprano' is the wordplay.
'in favour of' becomes 'for' (being for a particular cause).
'drink' becomes 'sake' (sake is a kind of drink).
'soprano' becomes 's' (musical abbreviation).
'for'+'sake'+'s'='FORSAKES'
(Other definitions for forsakes that I've seen before include "Abandons" , "Deserts" , "Leaves in the lurch" .)