[bob1029]

The (presumably) low power demand means you could do pretty much anything... you could digitally control the frequency of the power to this clock if you ran your own inverter. Like in software you would know exactly how many cycles had elapsed since previous time and how many need to elapse before the next to achieve synchronization with some NTP source. There are all sorts of ways you could sort it out, assuming the clock is not mechanically slipping relative to AC cycles.