The term 'clock signal' refers to a type of electrical signal used to synchronize the operations of digital circuits. Two crossword solutions for this term are 'ALARM' and 'CHIME'. An ALARM is an audible signal, such as a bell or buzzer, that is used to alert people to a specific event or time. A CHIME is a similar sound, but it is usually more melodic and is often used to mark the passing of time. Both of these signals are commonly used in clocks and other timekeeping devices.