Related Clues:

• Leak source, perhaps
• Burrowing beast
• Small insectivorous mammal
• Burrowing mammal
• Intelligence agent
• 'The Taming of the ___'
• Planted agent
• Underground mammal
• Kate, to Petruchio
• Spy-in-hiding
• Suburban burrower
• Lawn tunneler
• Relative of a mole
• Burrowing critter
• Intelligence problem