Attendance Good at start of event (4)
I believe the answer is:
gate
'attendance' is the definition.
(thesaurus)
'good at start of event' is the wordplay.
'good' becomes 'g' (abbreviation).
'start of' suggests taking the first letters.
The initial letter of 'event' is 'e'.
'g'+'at'+'e'='GATE'
(Other definitions for gate that I've seen before include "Narrow opening" , "Access here" , "Kind of door as in wall or fence" , "Attendance; entrance" , "Number of people admitted to a sporting event" .)