With the "clip" tool you can clip by either a rectangle, polygon or circle.
Can you clip using an existing shape?
Say if you have 20 2D shapes and a complicated polygon over top, rather than having to trace the complicated polygon with the clip tool you could just select the polygon and go clip.
I no there is the clip surface tool, but this seems more orientated towards only having 2 objects selected, I just tried with mulitple objects and the program timed-out.