Initiate (5)
'initiate' is the definition.
(beginning is a kind of initiating)
This is the entire clue.
(Other definitions for begin that I've seen before include "Clandestine, furtive" , "Make a start" , "Monachem --" , "Israeli prime minister and Nobel Peace Prize winner, d. 1992" , "Israeli statesman" .)
'initiate' is the definition.
(I know that initiate is a more specific form of the action initiate)
This is all the clue.
(Other definitions for originate that I've seen before include "In spring" , "issue" , "Create, initiate" , "Bring into existence" , "Create; begin" .)