How many letters does the top answer for “a place where the wicked are punished after death” have?

The most common answer is gehenna (7 letters).

Crossword clue: a place where the wicked are punished after death

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

gehenna 7 letters wn-def

a place where the wicked are punished after death

tartarus 8 letters wn-def

a place where the wicked are punished after death