Possible Clues:

• For malicious act get old shoe first
• Boast about age as a spoiling tactic
• Herb imbibes a half-bottle while plotting it
• Vandalism in the era of the wooden shoe?
• Vandalism
• Act that gets a bog seat smashed up, say?
• Deliberate act of destruction
• Shoe with a little silver for sweetheart in ruin
• Wise taking in a damaged boat to vandalise
• Spy's deliberate destruction