Commencement, inception (6)
I believe the answer is:
This clue is a double definition.
'commencement' is the first definition.
(I know that commencement can be written as outset)
'inception' is the second definition.
(I've seen this before)
(Other definitions for outset that I've seen before include "Kickoff time?" , "Opening stage" , "Set out in the beginning" , "Beginning, start" , "origin" .)