How many letters does the top answer for “lacking in energy or will” have?

The most common answer is passive (7 letters).

Crossword clue: lacking in energy or will

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

passive 7 letters wn-def

lacking in energy or will

lacking energy or vitality 50% similar → debilitated, enervated

lacking vigor or energy 50% similar → anaemic, anemic

without energy or will 50% similar → limp, wilted