Possible Clues:

• "Calm down!"
• Stay calm -- don't go topless!
• Be modest as long as you don't lose temper
• "Don't get so excited!"
• Calm down and don't put too much money on that horse!
• Don't panic? Irony tops here with UK in mess!
• Stay cool
• Don't panic 24 across - it's said you're getting his torn rubbish
• Relax with 10 across? It's said you're getting on after finding most of 21 down!
• Contradictory advice about keeping cool?