What is the best way to fix a wooden table top to its pedestal leg?

A permanent fix would be to put a dob of Araldite epoxy glue in the hole (enough to fill the gaps in the thread and re-fix) and then screw or push to top back on. Once in place put the table on a hard floor and put weights on the top to hold it firmly together. Keep it stable and leave for two - four hours. Make sure you remove any dust/debris from the hole before you insert adhesive