How many letters does the top answer for “author of the oval portrait” have?

The most common answer is poe (3 letters).

Crossword clue: author of the oval portrait

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

poe 3 letters wd-fact-v3

United States writer and poet (1809-1849)

author of portrait of an artist 50% similar → hockney

author of the portrait of a lady 50% similar → james

wrote the oval portrait 50% similar → poe