Possible Clues:

• "Relax"
• Exhortation for a panicky person
• Make still (from lack of wind)
• Don't get the wind up and keep your cool
• Become motionless in the main
• Still amble desultorily around clubs
• Make quiet or still - that's an order?
• It might be like this to get no sale, by the sound of it
• Mabel C (anag.)
• Make still - sounds like an order