Charge everyone, say, at the start of event (6)
I believe the answer is:
allege
'charge' is the definition.
(thesaurus)
'everyone say at the start of event' is the wordplay.
'everyone' becomes 'all' (all people).
'say' becomes 'eg'.
'at the start of' suggests taking the first letters (I've seen 'at the start' mean this).
The initial letter of 'event' is 'e'.
'all'+'eg'+'e'='ALLEGE'
(Other definitions for allege that I've seen before include "Aver (without proof)" , "Swear" , "Declare without actual proof" , "Declare or accuse without proof" , "Make accusation without proof" .)