How many letters does the top answer for “call in an official matter, such as to attend court” have?

The most common answer is summon (6 letters).

Crossword clue: call in an official matter, such as to attend court

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

summon 6 letters wn-def

call in an official matter, such as to attend court

summons 7 letters wn-def

a writ issued by authority of law; usually compels the defendant's attendance in a civil suit; failure to appear results