I've had a couple of this style of plastic clip crack. Wrapping it in thread and then applying super glue seems to work pretty well. I also tried wrapping with fishing line, but it came undone pretty quickly. Just wanted to share the tip! Now if only I had a fix for when the prongs on the other half break off.
It looks like the thread is keeping the upper part from slipping out, yes. But that still creates vertical stress on the glued part. And the thread won't hold long either, is my prediction. It will loosen over time. Repairing something sometimes means replacing parts and that's the right approach here.
Yes, but temporary fixes are the most permanent.