Possible Clues:

• Repetition is, after all, Peter Piper's speciality
• Loan literati lively literary device
• Poetic ploy practised with panache!
• It's seen in some Shakespeare sonnets
• Something sometimes seen scanning sonnets?
• Delightful device diligently deployed, particularly in primitive poetry
• "Peck of pickled peppers," e.g
• Poetic device is nothing but repetition
• Did Daniel Defoe demonstrate this?
• This is what William Wordsworth wrote