How many letters does the top answer for “wrote mary poppins” have?

The most common answer is andrews (7 letters).

Crossword clue: wrote mary poppins

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

andrews 7 letters wd-fact-v3

United States naturalist who contributed to paleontology and geology (1884-1960)

travers 7 letters wd-fact-v3

a horizontal beam that extends across something

wrote mary poppins returns 75% similar → miranda

author of mary poppins 50% similar → andrews, travers

wrote mary stuart 50% similar → schiller