Causes or events of special significance (9)
I believe the answer is:
occasions
This clue is a double definition.
'causes' is the first definition.
(occasion can mean to cause or bring about)
'events of special significance' is the second definition.
'or' acts as a link.
(Other definitions for occasions that I've seen before include "Causes to happen" , "Special times or events" , "Social events" , "Celebrations" .)