Lost pressure after "clunk" sound in pipe
It sounds like an old system with washers, where a washer has come loose, or possibly some object, e.g. a corroded-off screw head, is being pushed into the outlet pipe when the tap is turned on fast enough to move it.

If you shut the supply below the sink and take the valve apart, the issue should be obvious unless it's an object that drops out of sight down the pipe. In that case, carefully turn the shut-off valve on a bit, after first covering the valve opening with a plastic bowl to redirect most of the water back into the sink. Hopefully, this will eject any blockage. You might need a helper to hold that bowl.