Historical clue formulations

• Pickle — 2019-08-25
• To eat a late lunch or wait until dinner, say — 2018-10-10
• Catch-22 — 2004-10-22
• It may have horns — 2002-08-25
• Thorny problem — 2000-06-27
• Horned thing? — 1999-10-20
• Catch-22 — 1994-02-20