How to best secure claw foot tub feet
It looks like part of the retainer has snapped off here



It may be possibile to have a new retainer fabricated or to have these repaired.

If all the feet have broken retainers take a gel cast of the attachment and then from that make a plaster cast so that the welder has something to fabricate a part to match up with. Alternatively you take the whole tub instead.

Two-part xpoxy glue is probably an easier solution and will probably last long enough to not be a problem.