What does a flashing white light on the ground mean for an aircraft with radio failure?

A flashing white light on the ground specifically indicates that an aircraft with radio failure should return to the starting point at the airport. This signal serves as a means of communication in situations where the pilot is unable to establish radio contact. When a pilot cannot communicate with air traffic control, the flashing white light acts as guidance for the aircraft's next move, ensuring safety and adherence to proper procedure without relying on radio communication.

In the context of the other choices, holding position does not apply here, as that's typically indicated by a steady light or a specific ground command in non-radio failure scenarios. Being cleared for takeoff or cleared to land involves active communication from air traffic control, which would not be the case for an aircraft in radio failure. Therefore, flashing white is a distinctive signal specifically instructing the pilot to return to the starting point rather than any other actions related to takeoff or landing.