Act dismissed from assembly (7)
I believe the answer is:
turnout
'assembly' is the definition.
(I've seen this before)
'act dismissed' is the wordplay.
'act' becomes 'turn' (a routine or performance).
'dismissed' becomes 'out' (dismissed in cricket).
'turn'+'out'='TURNOUT'
'from' acts as a link.
(Other definitions for turnout that I've seen before include "Attendance figure" , "Number of people attending an event" , "The crowd appearing at an event" , "Expel" , "Eventuate; dismiss" .)