How many letters does the top answer for “(british informal) very chic” have?

The most common answer is groovy (6 letters).

Crossword clue: (british informal) very chic

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

groovy 6 letters wn-def

(British informal) very chic

swagger 7 letters wn-def

to walk with a lofty proud gait, often in an attempt to impress others

(british informal) very poor in quality 50% similar → ropey, ropy