How many letters does the top answer for “wrote call me claus” have?

The most common answer is goldberg (8 letters).

Crossword clue: wrote call me claus

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

goldberg 8 letters wd-fact-v3

United States cartoonist who drew intricate diagrams of very complicated and impractical contraptions that accomplished

author of call me claus 60% similar → goldberg

composer of call me claus 60% similar → goldberg

wrote they call me trinity 50% similar → spencer