Possible Clues:

• Give the walls a new look
• Cover over
• Decorate from top to bottom, or vice versa
• Prepare to cover the walls again
• One copying material, needing to decorate
• Again decorate harvester, involving paint initially
• Farm worker accepts pressure to renew wall-covering
• Apply new wall covering
• Decorate again (palindrome)
• Whichever way you look at it, you'll have to decorate again