Clearance Sacrifice
In chess, a clearance sacrifice is a tactical motif which involves a square on the chessboard being vacated to open up lines of attack. The tactic may also result in the substitution of a piece hindering the attack by a piece useful to the attack.
In the following position I was able to unleash a clearance sacrifice that led to victory.
Be sure to tell us in the comments about one of your favorite clearance sacrifices.