Related Clues:

• Not certifiable, so to speak
• Hard to fluster
• Far from flustered
• Imperturbable
• Right upstairs
• Neither nuts nor crackers
• Sedated
• No-nonsense
• With it, mentally
• Not mad
• Lucid, mentally
• Not nervous
• Untouched?
• It may precede a storm
• Halcyon