The Grandfather Clock can be found next to the window front in the Mansion's Study. Setting the hands to six o'clock, the clock case will open and play a short alarm fanfare.
This otherwise trivial event provides us with a subtle clue for a later puzzle in the game: Once we've opened up the Sarcophagus by placing seven Serpent Statuettes on the indentations in front of it, our path leads us to a spacious hall whose walls are engraved with various dragons and knights. Its floor is covered with a large clock. With the help of two levers, we can set its hands to six o'clock, which will unlock a door on the opposite end of the room and allow us to enter the grounds where Hawk is imprisoned.
Adam: Hand's not working. But it's still ticking. Doesn't make any damn sense.