Explanation

You have a dangerous passed pawn on the seventh rank (or on the second rank for a black pawn), one step away from promoting to a new queen - but the promotion square is blocked by a piece. In the following diagrams, you can see different ways of removing the blocker in order to promote your pawn:

In the first diagram, your own piece blocks the promotion square. The white rook can move out of the way of the pawn. The move indicated by the arrow achieves this with check, ensuring promotion on the next move: 1.Rd8+ Kc7 2.a8=Q. This is called clearance.

In the second diagram, the opponent's piece blocks the promotion square. The rook can give check to force the black king away. By attacking the blocker, the rook also guards the promotion square, so the pawn can promote safely on the next move: 1.Rd8+ Kc7 2.b8=Q+.

Clearance is similar to a discovered attack or discovered check, in that you move one piece to reveal a threat of another piece. For a discovered attack or check that threat is a direct attack or check. For clearance, that threat can be checkmate, or some other tactics.

A clearing move can be especially strong if it is a forcing move, for example a capture, a check, or an attack. In that case, the opponent often cannot handle that forcing move, and the revealed threat at the same time.

In this level the revealed threat is the promotion of a pawn. You move one piece out of the way of your pawn, so the pawn can promote on a subsequent move.

Examples

White can play 1.Bd5! to clear the way for the pawn and guard a2. In the game, Black resigned, seeing that promotion couldn't be prevented.

Sometimes the clearing move can be a sacrifice:

Black can win with the clearance sacrifice 1...Rf1+! 2.Kxf1 h1=Q+. Any other move loses the pawn; for example, 1...Ke6? 2.Kg3.

Here is a more difficult example:

Black has two rooks for a queen, and the a pawn is one square away from promotion. There are seven ways to move the rook and clear the promotion square. However, White is threatening a perpetual check with the queen on the 6th rank. Only 1...Rg1! prevents the perpetual check, for example 2.Qe6+ Kh8 3.Qf6+ Rg7. If White captures the rook, Black can promote with check, for example 2.Kxg1 a1=Q+ 3.Kg2 Qa7 and the queen can help to defend against checks.

Related motifs

You can also combine clearance with other motifs: