>The game doesn't tell you (*cough*) but there is a minimise button in the lower right of the menu.

I already saw that, but I used it in an area without objects or interaction, so it had about the same effect as closing the menu and I thought "what's that for then?" and dismissed it.

>I'm reluctant to have anything lock the clonk in a certain state (like click at x,y and the clonks digs until there or click tree and the clonks chops until chopped).

This would probably be a bad idea anyway. In case of digging I think that the most annoying thing is the delayed animation. A "keep doing what I am doing at the moment"-button could be nice though.

>Not only is this error-prone (stucking permanently in a certain state) but it is a slight contradiction to your previous issue: not having full control over the clonk at all times. You'd need some kind of cancel button.

I'd cancel it by clicking "use" again. Why not have the tree offer a "chop tree" interaction if you have the axe selected? This would also to some extent eliminate the problem that you have to estimate the correct chopping distance before swinging at the tree.

>Games with a similar control scheme than clonk (to me my knowledge) also don't seem to take this path. In Terraria / Minecraft, you also have to hold down the mouse button to mine / chop trees

That may be true, but in shooters it is common to have a "toggle crouch" button for example. Also, digging and chopping were good in previous Clonk titles as well. Still, I'd rather fix animation problems first, before considering a change in the control scheme.