Related Clues:

• Storm antecedent
• Hard to fluster
• Unfashionable
• Far from flustered
• Imperturbable
• Oversedated, maybe
• Without without with
• Not clean
• Diamond declaration
• It's said with a thumb in the air
• See 20-, 38- and 54-Across
• Asleep
• Gone for the day
• 8-Down, publicly
• Not nervous