Possible Clues:

• Authors' pseudonyms
• Mark Twain and Saki, for two
• Mark Twain and Saki
• Writers' aliases, and what are found at the starts of the answers to the starred clues
• Crosaire, for one
• Lewis Carroll and others
• George Sand and others
• Mark Twain and George Orwell, e.g.
• All like Crosaire
• Writers' pseudonyms