One following Southern US soccer unusually (9)
I believe the answer is:
successor
'one following' is the definition.
(thesaurus)
'southern us soccer unusually' is the wordplay.
'southern' becomes 's' (abbreviation).
'unusually' indicates anagramming the letters.
'us'+'soccer'='ussoccer'
'ussoccer' with letters rearranged gives 'uccessor'.
's'+'uccessor'='SUCCESSOR'
(Other definitions for successor that I've seen before include "One following another" , "New leader" , "one coming after you" , "Heir" , "One taking over from another" .)