"Get started!" (5)
I believe the answer is:
begin
'get started' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for begin that I've seen before include "Israeli prime minister who shared the Nobel Peace Prize with President Sadat" , "Israeli statesman" , "Partly open" , "Monachem --" , "Initiate" .)