Level prior to tense incident (5)
I believe the answer is:
event
'incident' is the definition.
(an incident is an event or happening)
'level prior to tense' is the wordplay.
'level' becomes 'even' (similar in meaning).
'prior to' is a charade indicator (letters next to each other).
'tense' becomes 't' (abbreviation used in many dictionaries).
'even'+'t'='EVENT'
(Other definitions for event that I've seen before include "Something going on" , "match" , "game, perhaps" , "Something that happens - part of a programme?" , "special occasion" .)