International performance not broken up (6)
I believe the answer is:
intact
'not broken up' is the definition.
'international performance' is the wordplay.
'international' becomes 'int'.
'performance' becomes 'act' (act is a kind of performance).
'int'+'act'='INTACT'
(Other definitions for intact that I've seen before include "Undiminished" , "Entire and complete" , "Not broken or damaged" , "without flaw?" , "Undamaged, unimpaired" .)