How many letters does the top answer for “wrote foucault's pendulum” have?

The most common answer is eco (3 letters).

Crossword clue: wrote foucault's pendulum

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

eco 3 letters wd-fact-v3

author of foucault's pendulum 50% similar → eco

wrote the pit and the pendulum 50% similar → poe