Historical clue formulations

• Hard to understand — 2025-10-05
• See 19-Down — 2025-01-26
• Unintelligible — 2023-09-08
• Very confusing — 2018-11-20
• Opaque — 2015-11-01
• Poorly explained — 2011-03-05
• "Now I get it ... not!" — 2003-08-09
• Like an unhelpful explanation — 2001-02-09