One can be clear about it being a performance (7)
I believe the answer is:
recital
'a performance' is the definition.
(recital is a kind of performance)
'one can be clear about it' is the wordplay.
'one can be' indicates anagramming the letters.
'about' means one lot of letters goes inside another.
'clear' anagrammed gives 'recal'.
'recal' going around 'it' is 'RECITAL'.
'being' is the link.
(Other definitions for recital that I've seen before include "Concert by soloist" , "Chamber music concert" , "One's performance" , "Soloist's performance" , "Enumeration of facts" .)