Possible Clues:

• Undo by degrees
• Slowly break down
• Cause to gradually vanish
• Wear down recent royal elegy?
• Gradually destroy, as shoreline
• Riding 'e was so as to wear it away
• Wear in bad weather?
• Crumble into the sea, as shoreline
• Disappear slowly but surely
• What to do up in the broken reed is so wearing