If this broken clip is not totally removable from the door and replaceable from the manufacturer (looks like it is a different color than the door plastic around it), I would be concerned that glue or epoxy would not hold the broken off piece. The other side could also be an accident waiting to happen too.
Depending on what the original shelf support clip looks like and how it supports the shelf, you might be able to modify a short length “sleeve anchor” from Home Depot/Lowes. They are cheap also. You would need to drill a suitable hole for the sleeve anchor, through the broken hanger clip area (ensuring that your shelf would stay level after being rehung on the new sleeve anchor though).
There is not much space in the plastic door edge from your picture, but a sleeve anchor is all metal and a “very short depth version” should be able to mushroom up inside the door space to hold solidly in place. A suitable washer under the head of the sleeve anchor bolt may be enough to hold the fridge shelf securely with some mods/adjustment (depending on how the shelf hold mechanism works of course; like just a slot perhaps?). If it works on the damaged side, do the other side also and then you should have a little more strength overall for your shelf, and more piece of mind the shelf will be stronger than a glue job.
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