Related Clues:

• Gets 16-Across
• Matures a long time
• Stores in an oak cask, say
• Makes wine "fine"
• Numbers on some birthday cards
• Improves, as steak
• Gets ripe
• It's been a long time since know-alls lost the head
• 10 and 8 for Bart and Lisa Simpson, respectively
• Seasons, as firewood
• Numbers in family-photo captions, maybe
• Numbers on educational toys
• Improves naturally, as wine
• Real long time
• Some census numbers