Happened (8)
'happened' is the definition.
('occur' can be a synonym of 'happen')
This is all the clue.
(Other definitions for occurred that I've seen before include "Took place" , "Happened" , "Came to pass" .)
'happened' is the definition.
(befalling is a kind of happening)
This is all the clue.
(Other definitions for befallen that I've seen before include "Came to pass" , "(Having) happened to (someone)" .)
'happened' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for arose that I've seen before include "Cropped up" , "Emerged from" , "Became apparent" , "Came about" , "Followed" .)