How many letters does the top answer for “an obnoxious and foolish and loquacious talker” have?

The most common answer is chatterbox (10 letters).

Crossword clue: an obnoxious and foolish and loquacious talker

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

chatterbox 10 letters wn-def

an obnoxious and foolish and loquacious talker

prater 6 letters wn-def

an obnoxious and foolish and loquacious talker