Related Clues:

• Finger board?
• Stick-to-it-iveness
• Doggedness
• Miner's quarry
• Source of iron
• It may have a silver lining
• Classic suit
• Nail filer
• Tram filler
• Polishing substance
• Nerve
• See 32-Across
• It's fine for a refinery
• Pay dirt
• Common stain