Business agent following player (6)
I believe the answer is:
factor
'business agent' is the definition.
(I've seen this before)
'following player' is the wordplay.
'following' becomes 'f' (used when citing page numbers etc).
'player' becomes 'actor' ('actor' can be a synonym of 'player').
'f'+'actor'='FACTOR'
(Other definitions for factor that I've seen before include "Level on sun-screen scale" , "something that may affect result" , "Circumstances" , "Reason" , "One circumstance that contributes to a result" .)