Related Clues:

• Mentally sound
• Level-headed
• Not certifiable, so to speak
• Right upstairs
• Neither nuts nor crackers
• Hardly frivolous
• Very serious
• With it, mentally
• Not mad
• Lucid, mentally
• Untouched?
• Court-appointed psychiatrist's ruling
• Undisturbed?
• Well-thought-out
• Not missing any marbles