In baseball, "double clutch" refers to when a fielder fakes or attempts to throw the ball, but then pulls back before actually throwing it. The phrase is taken from automotive terminology, where it refers to the act of shifting gears. A player may double clutch by accident or on purpose. The former may occur if the player does not have a good grip on the ball or suddenly realizes he or she is about to throw to the wrong place. The latter may occur if the fielder wants to hold a runner on base by pretending to throw the ball to the base to which the runner wants to advance.
This type of move is not used on purpose very often, mostly because of the speed of major league players. Since they are so fast, keeping a player on base with a fake is less effective because once the runner realizes where the ball is going, he may still make it to base. However, it could be used effectively by an outfielder with a reputation for having a strong arm and successfully making long, accurate throws.