Preferred winding route via south of France (9)
I believe the answer is:
favourite
'preferred' is the definition.
('favourite' can be a synonym of 'preferred')
'winding route via south of france' is the wordplay.
'winding' indicates an anagram.
'south of' is a charade indicator (letters next to each other).
'france' becomes 'f'.
'route'+'via'='routevia'
'routevia' is an anagram of 'avourite'.
'avourite' put after 'f' is 'FAVOURITE'.
(Other definitions for favourite that I've seen before include "royal confidant" , "Specially dear person - likely winner" , "Beloved pet" , "leading contender" , "Most liked" .)