Possible Clues:

• Two animals closer?
• Area of water left worker needing material for fixing leaks
• Material blocking leaks
• Proofing agent works, though not initially, under water
• Material to prevent leakage
• Finish protector
• Builders' material is transported round a US city
• Water leak's beginning — worker gets this?
• It'll fill a hole
• Substance for closing something tightly