How can I delete everything outside of a clipping mask?

What I did is rasterized the contents then cropped. This only works if you do not plan on manipulating the image. But it does save a lot of file size.

Jerome,

Another thought: if the real issue is this,

"Can't move the objects. The requested transformation would make some objects fall completely off the drawing area."

rather than an actual need for deletion of invisible parts, the issue may be caused by something that may be found far away from the Clipping Mask and easily dealt with. Ctrl/Cmd+A may give a clue. There may also be something related to Guides, I believe.

Jerome,

1) In the Transparency palette/panel dropdown list select anything but Normal (Multiply is fine; this step may be unneeded in your version, you may try without it);

2) Object>Flatten Transparency, just keep the defaults including 100% Vector;

3) Shudder (optional, unless unavoidable).

This will crop everything to the Clipping Path (or to its Bounding Box in case of raster images), with the possible exception of some empty paths, remnants of the pattern tiles that have been cut to fit the Clipping Path, or something similar; if there are such paths, you may:

4) With the Direct Selection Tool, Click an empty spot to deselect, then ClickDrag along and outwards from each side of the former Clipping Path and press Delete (twice) to get (completely) rid of the empty paths;

With this, everything should be cleaned up.

You could rasterize the file in Photoshop and then crop the image down to the clipping mask edges. You could also place the image into InDesign and only show the area desired. Both of these options are to get it to print now. It will not change the originating file.

If you have to edit the original, then I revert to Kurt's question about what is in the clipping mask?

That mainly depends on the contents of the clipping mask (what different kind of objects does it contain?).

It may be possible or not. Or just partiallly.

Can you share a sample .ai file?