A watchmaker, as the name implies, works primarily on watches, not clocks. Some watchmakers work on clocks, but the skills and tools needed to work on a watch are not always applicable when working on a clock.
Historically, in England, watchmakers would have to undergo a seven-year apprenticeship and then join a guild, such as the Worshipful Company of Clockmakers in London, before selling their first watch. In modern times watchmakers undergo training courses such as the ones offered by the BHI, or one of the many school around the word following the WOSTEP curriculum.
Richard Dawkins later applied this analogy in his book The Blind Watchmaker, arguing that evolution is blind in that it cannot look forward. Evolution, says Dawkins, is not directed by god(s). Instead, all intricate improvements in nature's mechanisms stem from survival pressures.
In the scifi novel The Mote in God's Eye by Larry Niven, the Watchmakers are a small technologically intelligent sub-species of the Moties that will repair/improve things you leave out for them (accompanied by food as payment).
Albert Einstein, in discussing the advances of the nuclear era, noted that, "[t]he release of atom power has changed everything except our way of thinking... the solution to this problem lies in the heart of mankind. If only I had known, I should have become a watchmaker."