Related Clues:

• Aim of medical research, often
• Fundamental
• Essential part
• Informal shirt
• Dry, as tobacco leaves
• Medical discovery
• Join together
• Furrow, as the brow
• ___-all
• Sweater, maybe
• Fix socks
• Stocking cap, for example
• It's below the mantle
• Tricot, for one
• Central part