Historical clue formulations

• Whiz — 2019-08-04
• Aficionado — 2018-04-09
• Black belt, e.g. — 2017-09-14
• Old hand — 2014-12-02
• Know-nothing's opposite — 2011-02-07
• Pro — 2010-10-01
• Puzzle-solving level — 2006-09-08
• Whiz — 2003-11-27
• Masterful — 2002-08-14
• Black belt, say — 1999-01-29
• Master hand — 1997-01-17