Related Clues:

• Group of vipers
• Concavity
• Make a home, in a way
• Snug spot
• Twiggy digs
• Long groove
• Endless 9-to-5 job, e.g.
• Wasps' home
• Avian abode
• Branch structure
• Fit within one another
• Track in the ground
• It's boring to be in one
• Place in the woods
• You might get in this at work