Agent of fine performer (6)
I believe the answer is:
factor
'agent' is the definition.
(business term for a representative)
'fine performer' is the wordplay.
'fine' becomes 'f' (abbreviation).
'performer' becomes 'actor' (actor is a kind of performer).
'f'+'actor'='FACTOR'
'of' is the link.
(Other definitions for factor that I've seen before include "Circumstance that influences result" , "Of 15, 3 or 5" , "Component, element" , "Aspect" , "one to be taken into account" .)