Related Clues:

• Tunnel, essentially
• 19th ___ (post-round hangout)
• Ice fisher's creation
• One of the front nine
• This in one is a golfer's dream!
• Ozone layer problem
• Drain opening
• Empty space; aperture
• One of 18 on a course
• One of 18
• What a dog digs
• Part of a doughnut
• Something to dig
• It's dug
• Leaky boat cause