Clue: Lunatic overcome by boundless ocean, misrepresented? (6)
Answer: CANUTE
Explanation: Lunatic overcome by boundless ocean, misrepresented? (6)
An envelope ('overcome by') of NUT ('lunatic') in CAE, an anagram ('misrepresented') of '[o]cea[n]' minus its outer letters ('boundless'). If you are not familiar with the story referenced in the &lit definition, try .