Possible Clues:

• Pseudonymous novelist retired, lacking energy - goodbye to love
• 'A Dog of Flanders' novelist, 1872
• Her sister mourned becomingly
• Bilingual agreement for Louise Rame
• She wrote agreeably in two languages
• ''Under Two Flags'' novelist
• A Dog of Flanders writer
• Some of you, I daresay, will identify a bestselling novelist
• One-named author of 1867's 'Under Two Flags'
• One-named author of 1867's "Under Two Flags"