is it a single click, or sort of a fluttering series of clicks. the fluttering sound is when your not getting enough voltage/amperage to the starter, and the relay just flutters back and forth.
it could be a bad battery, dirty terminals at the battery, or dirty terminals on the ends of the big cables at the starter or ground point.
turn on your headlights and dome light, and then try to start it. do the lights go dim, if so its probably a bad battery. parts store can to a load test to prove good/bad.
if nothing wrong with battery, the clutch switch is probably not expensive, just replace it