Possible Clues:

• A petty formality, perhaps, to fudge the topic until tea is taken.
• Particular joke, one getting fired after a setback in company
• Minute ceremonial detail
• Petty formality that may turn out to be unpolitic
• Strict observance of formalities
• Joke? Muse about it reflecting what strict etiquette demands
• Petty detail in incomplete clue I point out
• Fine point unpolitic to fiddle with
• Petty rule it could be unpolitic to break
• Meticulous without you and me in strict observance of etiquette