How many letters does the top answer for “becoming less or smaller” have?

The most common answer is decreasing (10 letters).

Crossword clue: becoming less or smaller

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

decreasing 10 letters wn-def

becoming less or smaller

a becoming gradually less 50% similar → dwindling

becoming smaller or less or appearing to do so 50% similar → diminishing

the act of becoming less 50% similar → shrinking