How many letters does the top answer for “a man who is very old” have?

The most common answer is graybeard (9 letters).

Crossword clue: a man who is very old

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

graybeard 9 letters wn-def

a man who is very old

methuselah 10 letters wn-def

a man who is very old

a very old person 50% similar → antediluvian

a very wealthy man 50% similar → croesus

an old man; a graybeard. 50% similar → whitebeard

an old man. shak. 50% similar → graybeard