This can be useful when you want to be able to tweak the postions of numerous images within a clipping mask without having to delete areas and edges of images.

1. Create the shape which will act as your clipping mask on a blank Photoshop canvas. For this example draw a circle.
2. Paste a new image over your ciclular clipping mask shape. This will create a new layer in your layers palette.
3. Draw a square path with your vector shape/drawing tool over the image (you must create it as a path and not a shape). Select the path with your ‘Path Selection Tool’, right click and ‘create vector mask’. Your image should now be masked by this square vector path.
4. Make this a clipped path within the circular shape right click (alt-click for mac) and select ‘create clipping mask’ (or pressing Ctrl+Alt+G). Ta-da, you should now have a mask inside a mask.
5. You can create multiple clipped vector shape layers by stacking them one on top of another in the layers palette as you turn them into clippling paths.
6. To move the images around inside your vector masks you musk unlink them in your layers palette. To scale images inside masks you will need to deselect the mask (pen icon) on the layer in the layers palette.