How many letters does the top answer for “wrote dr. mabuse the gambler” have?

The most common answer is lang (4 letters).

Crossword clue: wrote dr. mabuse the gambler

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

lang 4 letters wd-fact-v3

Long. [Obs. or Scot.]

author of dr. mabuse the gambler 60% similar → lang

director of dr. mabuse the gambler 60% similar → lang

wrote the gambler 50% similar → dostoyevsky