How many letters does the top answer for “author of bonjour tristesse” have?

The most common answer is sagan (5 letters).

Crossword clue: author of bonjour tristesse

1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

sagan 5 letters wd-fact-v3

director of bonjour tristesse 50% similar → sagan

wrote bonjour tristesse 50% similar → sagan