Possible Clues:

• Organic compound; to knee (anagram)
• Chemical providing vital firmness of bodily tissues, we hear
• Chemical's essential quality featured in report
• Organic compound used in solvents
• ... simplest compound of its kind is a piece of cake to 18
• Acetone or fructose
• Compound used in solvents
• Camphor, e.g
• The liver produces it to break down fats for energy
• Organic compound in solvents