Got a heavy clutch? maybe weak hands? the Clutch Buddy might be useful to you.
It’s an easy to install device that keeps your clutch pulled in while giving your hand a rest. You pull in the clutch lever, flip your thumb on the toggle and a spring-loaded hook comes up and holds the lever for you. A flip of your thumb releases the clutch again.
A simple option is from a Yamaha quad bike where the left hand lever is a brake which has a small spring-loaded lever which can be flipped down to hold the lever against the bar.
As soon as the lever is pulled, it flips up.