Related Clues:

• Yellows or grays
• Improves, as whiskey
• Nears retirement
• Important periods
• They may be checked at the door
• Bronze and Iron, e.g.
• Ever so long
• Becomes drinkable, perhaps
• Grows old gracefully
• Iron and Bronze, e.g.
• They change every year
• Iron and Stone
• Matures, as wine
• Middle __
• Improves, as some cheese