Divert from southern route (4)
I believe the answer is:
sway
'divert' is the definition.
(thesaurus)
'southern route' is the wordplay.
'southern' becomes 's' (abbreviation).
'route' becomes 'way' (way is a kind of route).
's'+'way'='SWAY'
'from' is the link.
(Other definitions for sway that I've seen before include "Swing from side to side, or influence opinion" , "Swing - lean - persuade" , "Influence; rule" , "Oscillate" , "Power - rock" .)