This article teaches you how to crop clipping mask, crop out all the extra empty space made by big transparent bounding box around the image to just leave the image as object in Illustrator.

You may expect a one-click button to do that, but unfortunately, in Illustrator, you can’t. But there is a work-around,

1. With the image and clipping mask still selected, in the transparency palette select any mode other than ‘Normal’.
2. Select Object > Flatten Transparency. Set the Raster/Vector Balance to 100 (Raster). Click ‘OK’.
3. Now if you ungroup, release the clipping mask, the original masked image area won’t be visible.

Hope this helps! :)