How many letters does the top answer for “the act or practice of duping.” have?

The most common answer is dupery (6 letters).

Crossword clue: the act or practice of duping.

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

dupery 6 letters web-def

something intended to deceive; deliberate trickery intended to gain an advantage

the act or practice of jesting. 50% similar → jocantry

the act or practice of poisoning. 50% similar → venefice

the act or practice of regrating. 50% similar → regratery