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

The most common answer is bloch (5 letters).

Crossword clue: wrote psycho

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

bloch 5 letters wd-fact-v3

United States composer (born in Switzerland) who composed symphonies and chamber music and choral music and a piano sona

hitchcock 9 letters wd-fact-v3

English film director noted for his skill in creating suspense (1899-1980)

wrote 1q84 50% similar → murakami

wrote 2666 50% similar → bolano

wrote 4 3 2 1 50% similar → auster

wrote q11368 50% similar → kernighan, ritchie

wrote q13415681 50% similar → hamill

wrote q134773 50% similar → zemeckis

wrote q1457000 50% similar → knuth

wrote q16276 50% similar → roddenberry