Related Clues:

• Willingness to get dirty
• Book backbone
• Resoluteness
• Liberal, so to speak
• Dogged determination
• "True __": John Wayne film
• Chiropractor's target
• Wayne's was "True"
• Book backing
• Abrasive bits
• Hedgehog feature
• Book back
• Sandpaper specification
• Sandpaper coarseness measure
• Personal column?