How many letters does the top answer for “small coffee cup; for serving black coffee” have?

The most common answer is demitasse (9 letters).

Crossword clue: small coffee cup; for serving black coffee

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

demitasse 9 letters wn-def

small coffee cup; for serving black coffee

a small cup for, or of, black coffee. 80% similar → demitasse