How many letters does the top answer for “the act of passing from one state or place to the next” have?

The most common answer is passage (7 letters).

Crossword clue: the act of passing from one state or place to the next

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

passage 7 letters wn-def

the act of passing from one state or place to the next

transition 10 letters wn-def

the act of passing from one state or place to the next