Related Clues:

• Work on a bone, say
• Become rusty
• Impress indelibly
• Engrave deeply
• Use acid creatively?
• Chew like a rodent
• Eat (at)
• Diminish slowly
• Wear away by nibbling
• Chew, squirrel-style
• Diminish over time
• Shrink in increments
• Grind down
• Ingrain
• Emulate a rat