Possible Clues:

• Device storing angular momentum
• *Engine part (In this answer, note the first 3 letters + the last 3)
• Make off with list showing engine component
• Rotor storing power
• Heavy rotating part of engine
• Heavy revolving mechanism that increases a machine's momentum
• Welsh fervour about to be conveyed by aptitude for moving part
• Means of storing power
• Part of machinery that revolves to store kinetic energy
• Power store