Thanks Dave, yes that is exactly what I mean. The trouble I'm having is that I have this large image that I want to be a vector drawing, and layout is struggling to deal with the size of it (I'm aware I'm probably not using layout for it's intended use, but, I'm an artist!). I have done it before where I have rendered sections in Layout and then pieced them together afterwards, but because of the perspective, I'm struggling to do that for this piece.
When I've made a clipping mask in Layout, before rendering, is it possible to detach this section so that it isn't masking, but it's its own entity?
Thanks for your help!