Level before start of throwing competition (5)
I believe the answer is:
event
'competition' is the definition.
(I've seen this before)
'level before start of throwing' is the wordplay.
'level' becomes 'even' ('even' can be a synonym of 'level'**).
'before' is a charade indicator (letters next to each other).
'start of' indicates taking the first letters.
The initial letter of 'throwing' is 't'.
'even'+'t'='EVENT'
(Other definitions for event that I've seen before include "celebration?" , "important" , "Something going on" , "Meeting" , "one item in programme" .)