The Collaborative International Dictionary of English v.0.48:

Stirrer \Stir"rer\, n.
   One who, or that which, stirs something; also, one who moves
   about, especially after sleep; as, an early stirrer. --Shak.
   [1913 Webster]

   Stirrer up, an instigator or inciter. --Atterbury.
      [1913 Webster]