Happening, occurrence (5)
I believe the answer is:
event
This clue is a double definition.
'happening' is the first definition.
(I've seen this before)
'occurrence' is the second definition.
(I've seen this before)
(Other definitions for event that I've seen before include "Occasion; sports contest" , "game, perhaps" , "Function" , "Fixture" , "A notable occurrence or happening" .)