Related Clues:

• Lack of practice, metaphorically
• Enemy of your car's chrome bumper
• Pipe problem
• Film
• Fall shade
• The green stuff on copper
• Oxidize
• Copper finish
• Age, in a way
• Corrosion on a statue
• Autumnal hue
• Sign of inactivity
• Iron oxide
• Used car problem, sometimes
• Red coat?