Possible Clues:

• It's hard to say
• Tricky phrase
• Phrase difficult to say
• It's hard to say to utter swine, out drinking gallons
• Perhaps French man not to be trusted? It's hard to say
• Speaker's challenge scrambled three times in this puzzle
• "She sells seashells," for example
• The starts of 20-, 29-, 36- and 46-Across, e.g., when repeated quickly in order
• 'Peter Piper picked a peck...' for one
• Difficult-to-say phrase