My MacBook Air is making a clicking noise

Does it persist if you mute the sound output? The idea is to determine if the sound is coming from your Mac's built-in speakers or something else.

The only moving part in an Intel MacBook Air is its exhaust fan. You can use Apple Diagnostics to exercise it: Diagnose problems with your Mac - Apple Support. If you correlate the noise to the fan, the cause is usually a contaminant such as an accumulation of dust. They can be cleaned. Get Support if you arrive at that conclusion.