How many letters does the top answer for “wrote banana joe” have?

The most common answer is spencer (7 letters).

Crossword clue: wrote banana joe

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

spencer 7 letters wd-fact-v3

English philosopher and sociologist who applied the theory of natural selection to human societies (1820-1903)

author of banana joe 50% similar → spencer

composer of banana joe 50% similar → spencer

director of banana joe 50% similar → spencer