Possible Clues:

• "To __ own self be true": "Hamlet"
• What used to be yours?
• Quaker's 'yours'
• Slender key was yours once
• Old pronoun
• Feeble echo is yours
• '...only with ___ eyes'
• It was yours at one time
• 'Were -- That Special Face'
• 4U, by the sound of it, a spare E, perhaps