How many letters does the top answer for “cry like a cat” have?

The most common answer is meow (4 letters).

Crossword clue: cry like a cat

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

meow 4 letters wn-def

the sound made by a cat (or any sound resembling this)

mew 3 letters wn-def

cry like a cat

to cry as a cat. shak. 50% similar → mew