Clay is a kind of earth that is soft when it is wet and hard when it is dry. Clay is shaped and baked to make things such as pots and bricks.

In tennis, matches played on clay are played on courts whose surface is covered with finely crushed stones or brick.

If you say that a person who is respected or admired has feet of clay or has clay feet, you mean that they have serious faults which you or other people did not know about before.