How many letters does the top answer for “military service scientist” have?

The most common answer is montagu (7 letters).

Crossword clue: military service scientist

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

montagu 7 letters wd-fact-v3

United States anthropologist (born in England) who popularized anthropology (1905-)

pavlichenko 11 letters wd-fact-v3

military scientist 67% similar → gelfand

civil service scientist 50% similar → constantinople

military affairs scientist 50% similar → butler, jomini, marcellinus

military history scientist 50% similar → ambrose, delbruck

retire from military service 50% similar → demob, demobilise, demobilize