Possible Clues:

• "Wait for it"
• Waiting periods?
• And so on
• Indication of more to come ... or a hint to a feature of three consecutive letters in 18-, 20-, 59- and 61-Across
• Ellipsis
• Ellipsis, informally
• Indication of more to come ... or what 17-, 28- and 43-Across all contain
• Continuation indication