How many letters does the top answer for “make ready for action or use” have?

The most common answer is marshal (7 letters).

Crossword clue: make ready for action or use

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

marshal 7 letters wn-def

a law officer having duties similar to those of a sheriff in carrying out the judgments of a court of law

mobilize 8 letters wn-def

make ready for action or use