A PlotRange specification will not clip the graphics as you already found out. Unfortunately there is no ‘clipping’ primitive as of yet, though I have requested it. In this case you can solve it by using a 3rd argument in Circle. This will not work in general for any primitive unfortunately…
Sometimes you can get away by using Overlay, or rasterizing your Graphics and then using ImageOverlay. Or using RegionUnion and (discretised) versions of your primitives along with your a rectangular viewing range region. To sum up: you have to be creative sometimes!
Thank you for the answer. I only thought there must be a solution, because PlotRangeClipping works fine, if there is some more space needed for axes and ticks:
But if there is no such solution, I try a workaround with hiding things with white Rectangles before drwaing on the “extra plotrange”. I will also study your other suggetions.