Possible Clues:

• Umlaut lookalike
• It tells you how to pronounce 'firesides' wrongly (without the 'f')
• The two dots in "naïve" or "Brontë"
• Mark missing from "naive"
• Umlaut doppelganger
• Mark policeman getting series recast
• I, perhaps, may be under it when small
• The two dots in 'naïve'