The clutch cable provides a means to "break the drive" between the engine and the wheels. The engine spins constantly, but the wheels do not, so in order to stop a car's wheels without turning off the engine, the wheels have to disconnect from the engine. When the clutch pedal is pressed, the cable disengages the plates, allowing the driver to shift gears or coast without killing the engine.
A failing clutch cable may make the clutch pedal difficult to depress. If the clutch cable fails, the clutch pedal may remain on the floor and not return to its normal position.
To replace the clutch cable, disconnect it from the clutch pedal (usually inside the vehicle) and from the release mechanism or cable attachment that operates the clutch assembly (usually at the transmission beneath the vehicle). A new clutch cable is then installed and adjusted. (The specifics vary according to the vehicle and range from straightforward to very difficult.)