Ticking Clock is one of the Chamber Dungeons found in Link's Awakening.
Ticking Clock is the twelfth Chamber Dungeon unlocked in the game. It one of four of the 'Level 3' Chambers. The chamber dungeon is unlocked after Link completes the Sheated Sword dungeon, as well as Turtle Rock in the main quest.
The dungeon starts with 6 pre-determined tiles, with three of them at the top and three of them at the bottom of the dungeon, requiring Link to use a staircase to connect the two sides. Other than that, it is a fairly open floor plan, so it is very easy to construct the rest of the dungeon. The trick with this particular dungeon is that when playing through the arranged dungeon, there is a time limit of just five-minutes. So it is best to place the least amount of tiles to complete the dungeon, along with rooms that are fairly easy to navigate.
Link will earn a Heart Container and the +Wallmasters Effect for arranging and then completing the dungeon. The Wallmaster Effect can later be placed when arranging dungeons. It will cause a Wallmaster to drop from the ceiling and if it captures Link, will take Link back to the entrance of the dungeon. Completing the dungeon also unlocks all twelve of the Level 4, "Golden" Dungeons.
You're on the clock with this one. The idea is to get to the boss and beat it in just five minutes. If you ask me, it comes down to how you place the entrance and the Nightmare's Lair. Not that anyone asked me.