Sorry no Halfway, but they cool bikes.
1. The hole is not threaded
2 The clamp and the shaped protrusion have similar shapes (one being male the other female) to maximize contact area.
This makes me think that a screw does not go there.
I suspect that the clamp tension may be adjusted by the nylock lock nut on the end of the spring shaft. But I am not sure.
Suggest you test, but if it doesn't work be sure to return it to its original position