Won't start periodically. Does not turnover

My 318 occasionally will not start. I don't even get a click when I turn the key which I thought I might get if it were a starter problem. Instead it is silent, there is power as gauges move and lights come on with the turn of the key. The frustrating part is that it has happens once every 5 -10 times I drive the car. The battery connections are tight. I would say it happens more often when hot. But it has happened when cold too.
It will start if I pop the clutch. Does that mean it is the starter alone or should I be looking elsewhere?

Is this a stick or automatic. The LAST thing I would do is "go buy parts" Learn to troubleshoot then you KNOW the first round.

If it's a stick, make certain the starter relay is grounded.

If it's an auto, "work" the shifter from P to N as you hold the key in "start" and listen for a reaction.

Learn to listen CLOSELY. Open the window or hood if you must. Listen for the small "click" the starter relay makes. If that happens and it does not start, and least you know the relay is activating.

When the trouble is showing, clip a meter or test lamp to the starter relay "push on" terminal which is the start wire coming from the ignition switch. See if you are getting power there. If so, and no relay action, THEN replace the relay.