Possible Clues:

• Cut around base of iron grate
• Grind together, of teeth
• Grit one's teeth
• Sounds like architect's hard grind
• Grind (teeth) together
• Grind (as teeth)
• Engage canines?
• 'It's a grind,' beau said
• No good turning over what's burnt in grate
• Hangs about - it's a grind