Shift AGM -- one vote for a change (3,1,4,2)
I believe the answer is:
get a move on
'shift' is the definition.
(I've seen this before)
'agm one vote for a change' is the wordplay.
'for a change' indicates anagramming the letters.
'agm'+'one'+'vote'='agmonevote'
'agmonevote' with letters rearranged gives 'GET A MOVE ON'.
(Other definitions for get a move on that I've seen before include "Hurry up (colloq.)" , "quickly!" , "Speed up" , "shift" .)