I think you are confusing “cutting/masking something” and “putting a rectangle on top of it”. The easiest way to crop an object in your case is to put it in a Frame and enable Clip Content in it, then scale the Frame down to the necessary size. You can also use a Mask but the result in SVG code would be slightly different.

Thanks for your reply, @Gleb

I managed to do it thanks to your indications.

Plus it’s important to mention that you need to hold command/control key while resizing the frame, so as to ignore the constraints, otherwise the content you want to crop might disappear because of the constraints.

I struggled a bit before finding this tip as well. but am now all set!

Hope this helps.

Best, Gonzo