How many letters does the top answer for “a soldier armed with a carbine.” have?

The most common answer is carbineer (9 letters).

Crossword clue: a soldier armed with a carbine.

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

carbineer 9 letters web-def

light automatic rifle

a soldier armed with a musket. 50% similar → musketeer

a soldier armed with a rifle. 50% similar → rifleman