How many letters does the top answer for “activity involved in maintaining something in good working order” have?

The most common answer is maintenance (11 letters).

Crossword clue: activity involved in maintaining something in good working order

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

maintenance 11 letters wn-def

activity involved in maintaining something in good working order

upkeep 6 letters wn-def

activity involved in maintaining something in good working order