Related Clues:

• Letter sign-off
• Much-watched interest rate
• First in the rankings
• Steak sauce choice
• ". . . in ___-horse open sleigh"
• _____ time
• Optimally rated
• Rib adjective
• Second-to-none
• Like a 63 Across?
• Top-level
• Most helpful
• Untoppable rating
• At the zenith
• Informal letter signoff