How many letters does the top answer for “a fervent and even militant proponent of something” have?

The most common answer is drumbeater (10 letters).

Crossword clue: a fervent and even militant proponent of something

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

drumbeater 10 letters wn-def

a fervent and even militant proponent of something

zealot 6 letters wn-def

a fervent and even militant proponent of something