Historical clue formulations

• A, for one — 2023-07-01
• One of seven in the Constitution — 2023-02-01
• A is one — 2021-08-01
• First word of the Constitution after the preamble — 2018-09-01
• Part of the Constitution — 2017-11-03
• Thing — 2015-10-11
• A, but not B or C — 2014-06-15
• What the Beatles had but Wings didn't? — 2013-10-24
• One of seven in the Constitution — 2012-12-10
• Time unit — 2011-03-26
• 57-Across offering — 2009-04-18
• "A" or "an" — 1998-12-21
• Time piece — 1995-11-26
• It may be indefinite — 1995-04-22