How many letters does the top answer for “a reddish to vivid orange color” have?

The most common answer is tangerine (9 letters).

Crossword clue: a reddish to vivid orange color

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

tangerine 9 letters wn-def

a reddish to vivid orange color

of a vivid red to reddish-orange color 80% similar → cinnabar, vermilion, vermillion

of a strong reddish orange color 60% similar → tangerine

of a reddish color. 50% similar → flammulated