Related Clues:
- 17's track opening
- Emerge from shell
- Emerge from egg - opening
- Aperture to sewer, duct etc
- Incubate - opening
- Access chamber to sewer or drain
- Opening with removable door
- Incubate — plan
- Cook up, as a plot
- Crack an egg?
- Break out of one's shell?
- Drain cover
- Sub door
- Deck opening; (egg) open
- Trapdoor cover