How many letters does the top answer for “an old man. shak.” have?

The most common answer is graybeard (9 letters).

Crossword clue: an old man. shak.

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

graybeard 9 letters web-def

a man who is very old

a man who is very old 50% similar → graybeard, methuselah

a military man. shak. 50% similar → militarist

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