Fine performance given (4)
I believe the answer is:
fact
'given' is the definition.
(thesaurus)
'fine performance' is the wordplay.
'fine' becomes 'f' (abbreviation).
'performance' becomes 'act' (act is a kind of performance**).
'f'+'act'='FACT'
(Other definitions for fact that I've seen before include "Item of truth" , "Piece of information known to be true" , "Certain thing" , "Undisputed item" , "Undisputed truth" .)