Possible Clues:

• Marcel ____, author of the unfinished novel Jean Santeuil
• Madeleine-inspired writer
• Head of Penguin right to sack author
• Writer needs pen initially to get going
• Novelist's written for American Time
• Writer in favour of American technique, initially
• Writer whose last name is spelled from a seven-letter span of the alphabet
• 'Swann's Way' novelist
• Marcel --, French novelist (1871-1922)
• Writer, mostly haughty when seen on street