How many letters does the top answer for “make barrels and casks” have?

The most common answer is cooper (6 letters).

Crossword clue: make barrels and casks

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

cooper 6 letters wn-def

a craftsman who makes or repairs wooden barrels or tubs

of a cask or barrel 67% similar → abroach, broached

one who makes barrels, hogsheads, casks, etc. 50% similar → cooper

small cask or barrel 50% similar → keg