It will eventually happen that an act gets banned (4,3)
I believe the answer is:
turn out
'it will eventually happen that' is the definition.
The definition suggests a singular noun but the answer is not.
'act gets banned' is the wordplay.
'act' becomes 'turn' (a routine or performance).
'gets' means one lot of letters go next to another.
'banned' becomes 'out'.
'turn'+'out'='TURN-OUT'
'an' acts as a link.
Can you help me to learn more?
(Other definitions for turn out that I've seen before include "parade" , "Eject" , "End up" , "Prove" , "All the voters" .)