It really depends upon the artwork.
If the art is comprised of a bunch of raster images with clipping masks you are sort of stuck. You can't crop, cut, or clip raster images within Illustrator - you can only mask them.
If the art is all vector and merely contains clipping masks.....
In some cases,
Object > Flatten Transparency will quickly "bake in" clipping masks. Beyond that, you may need to select individual masks and use
Object > Expand followed by
Pathfinder > Crop (the panel, not the effect menu).
This is generalizing, without seeing the file construction or layers panel expanded it's difficult to be more precise.