What is this clear liquid after braising?
I believe the liquid looks like fat that has been rendered out of short ribs, which are quite fatty. Most of the water-based liquids you added (red wine, stock, vinegar, etc.) seem to have evaporated and/or burned, and what's left of them has sunk to the bottom of the pan. Naturally, oil would float on top.
As to what to do with it, you could use it to cook, but keep in mind it will carry some flavours of this dish.

Update: OP just edited the original question to say the liquid solidified, confirming that it is indeed fat.