One following US soccer's development (9)
I believe the answer is:
successor
'one following' is the definition.
(thesaurus)
'us soccer's development' is the wordplay.
'development' indicates anagramming the letters.
'us'+'soccers'='ussoccers'
'ussoccers' anagrammed gives 'SUCCESSOR'.
(Other definitions for successor that I've seen before include "Person who follows next in order" , "One following another" , "One follows next in order" , "Follower (in post)" , "I follow" .)