Leven starred as a trialist in a couple of Under 21 matches at the end of last season and boss Jim Jefferies recognises that the player has enough ability to take a gamble on.
Meanwhile, Stevie Fulton has signed for Partick Thistle under similar circumstances after Killie stalled on a new deal waiting to see the 34 year-old's recovery from surgery.
On the injury frony, Paul di Giacomo is ahead of his recovery schedule, but won't feature in the first team until after Christmas.