Possible Clues:

• Confirmed that it's been made a pest
• 'Confirmed that one made a rodent of this, perhaps (8)'
• Formally approved and given legal authority
• Officially validated
• So it's been confirmed that it seems to have been made verminous
• Formally confirmed
• Of treaty, agreed and signed
• Given approval of having it made like the start of 10 across, perhaps
• Rodentated, perhaps, with approval
• Confirmed or accepted agreement or treaty