"Tick tock, on the clock, but the party don't stop." Ke$ha could just as well be singing about the ubiquitous clock that pops up all the way through Tristram Shandy. After all, Tristram's the way that he is because his father forgot to wind the clock. Time-keepers seem to stand in for a kind of order that links up with masculinity, potency, and plain, straight-up storytelling. Tristram is conceived under a stopped clock, which might explain why his sense of time is screwy.
And his obsession with clocks persists the whole way through the book. On Tristram's trip to Europe, one of the only things he wants to see is "the wonderful mechanism of this great clock of Lippius of Basil" in Lyons (7.30.2). Of course, once he gets to the cathedral, he learns that "Lippius's great clock was all out of joint, and had not gone for some years" (7.39.2). (BTW, the Lyons cathedral does have a centuries-old astronomical clock, dating back to the 1300s.) This second appearance of a stopped clock tips us off that time—and keeping it—really matters to Tristram.
All those stopped clocks link up with the theme of—Captain Obvious, here— "TIME." Tristram is constantly trying to catch up with himself through writing, but the process of writing is so digressive that he just falls farther and farther behind. You might say that clocks represent a harmonious union between time as it's passing and time as it's told. But Tristram Shandy doesn't run on clock time—it runs on narrative time, which never quite lines up. Life is lived faster than Tristram can write.