How many letters does the top answer for “wrote charlotte's web” have?

The most common answer is white (5 letters).

Crossword clue: wrote charlotte's web

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

white 5 letters wd-fact-v3

being of the achromatic color of maximum lightness; having little or no hue owing to reflection of almost all incident l

winfrey 7 letters wd-fact-v3

wrote web 67% similar → knuth

author of charlotte's web 50% similar → white, winfrey