Related Clues:

• Vent
• Lacerate
• Cat's eye, sometimes
• Gill opening
• Little cut
• Incision
• Narrow opening
• Buttonhole, e.g.
• Squinting eye, e.g.
• Cut open
• Skirt feature, perhaps
• Use a letter opener
• Eye opening for a squint
• Piggy bank feature
• Gash