Historical clue formulations

• Hit 1980s-'90s sitcom ... or what the circled letters in 16-, 26- and 43-Across represent? — 2018-07-10
• K-K-K-5-5, e.g., in poker — 2017-01-09
• *What "S.R.O." indicates — 2010-11-23
• 23-Across + 9-Down — 2002-06-23
• 37-Across beater — 1999-06-22
• Flush beater — 1997-06-30