Possible Clues:

• The plan is to have layers of precious stone
• Reject excellent pastries? It's a trick
• Turn strumpet into wise maiden? That's the plan
• Plan to unearth stone under rock layers
• A scheme
• Tactic to gain an advantage
• Plan to deceive enemy
• Manoeuvre layers of rock and stone
• Learned motorway is masking restaurant plot
• Plan to sabotage regattas on first of May