The clock will run slower at the bottom of a deep well than at the surface.
Work Step by Step
Strong gravitation expands time intervals, i.e., it slows down the passage of time. The clock in the well is closer to the center of the Earth than the clock at ground level, so it is in a stronger gravitational field. In other words, it is the decrease in gravitational potential that slows the clock. This is discussed on page 691.