How many letters does the top answer for “the activity of causing to have energy and be active” have?

The most common answer is activating (10 letters).

Crossword clue: the activity of causing to have energy and be active

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

activating 10 letters wn-def

the activity of causing to have energy and be active

energizing 10 letters wn-def

the activity of causing to have energy and be active