A pendulum clock was an ancient type of chronometer, consisting of a long weighted pendulum that swung side to side, making a distinctive tock sound every second.
One very expensive clock was kept by Queen Mother Tenel Ka Djo in her Special Salon on Hapes. In 40 ABY, Han Solo, Leia Organa Solo and C-3PO came to be in its presence while they were awaiting an audience with Tenel Ka. C-3PO assumed it to be pre-Lorellian, looted from a Balmorran colony ship by pirates. Han found the "tocking" to be so annoying that Leia had to restrain him from throwing a priceless larmal-topped end table at it.