How many letters does the top answer for “skill in an occupation or trade” have?

The most common answer is craftsmanship (13 letters).

Crossword clue: skill in an occupation or trade

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

craftsmanship 13 letters wn-def

skill in an occupation or trade

workmanship 11 letters wn-def

skill in an occupation or trade

the occupation and skills of a confectioner 50% similar → confectionery