I have a few tools called "trim removal tools" Here is one similar to my favorite:

http://www.clarks-garage.com/shop-manual/body-11.htm

The key is that they have a WIDE, FLAT blade, but it needs to be strong (not a 'putty knife') The wide surface distributes the force and prevents damage- a screwdriver will cut into the item or the liner, but a flat blade will not.

Looking at the clip, it will probably require quite a bit of force. If it breaks, you can always buy a new clip (and you are replacing the light anyway...)