Clockwork refers to the inner workings of mechanical timepieces such as clocks or pocket watches.
In 2366, Paul Stubbs noted that over and over again, the intense gravitational pull of a little neutron star, inside an unnamed binary star system in the Kavis Alpha sector, sucked up star material from its neighboring red giant which built up on the surface until it exploded every 196 years like clockwork. (TNG: "Evolution")