How many letters does the top answer for “author of swan lake” have?

The most common answer is petipa (6 letters).

Crossword clue: author of swan lake

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

petipa 6 letters wd-fact-v3

tchaikovsky 11 letters wd-fact-v3

important Russian composer whose works are noted for their expressive melodies (1840-1893)

author of the black swan 50% similar → taleb

author of the lady in the lake 50% similar → chandler

author of the lady of the lake 50% similar → scott

author of the trumpet of the swan 50% similar → white

composer of swan lake 50% similar → tchaikovsky

wrote swan lake 50% similar → petipa, tchaikovsky