Related Clues:

• Improve, as one's skills
• Perfect, as one's skills
• Coffee machine setting
• Sharpen, as on a whetstone
• Dreary routine
• Work on the edge?
• Make perfect
• Reduce to powder
• To crush or pulverize
• Make sharper
• Put to the grindstone
• Give the edge to?
• Crush into bits
• Apply to a whetstone
• Make more acute