Southern river lodge (4)
I believe the answer is:
stay
'lodge' is the definition.
(thesaurus)
'southern river' is the wordplay.
'southern' becomes 's' (abbreviation).
'river' becomes 'tay' (Scottish river**).
's'+'tay'='STAY'
(Other definitions for stay that I've seen before include "Supporting rope; remain" , "Supporting rod" , "Visit (for the night)" , "Check" , "Remain; prop" .)