Historical clue formulations

• Little confab — 2023-05-12
• "Just between us" talk — 2019-01-25
• One-on-one talk — 2017-05-08
• 17-Across, literally: Fr. — 2014-04-28
• Private chat — 2012-10-26
• Private chat — 2007-07-24
• Close communication? — 2007-05-16
• It's just between us — 2006-04-07
• Powwow — 2005-12-16
• Chat — 1999-01-08