Related Clues:

• Warty hopper
• First mistake
• Avarice, e.g.
• Major no-no
• Offense
• Go wrong
• Croaker
• Evil
• Pond denizen
• Vice
• 'The Wind in the Willows' character
• Kind of tax
• Warty-skinned critter
• Sloth, for one
• Confession in a confessional