How many letters does the top answer for “stick out or up” have?

The most common answer is bulk (4 letters).

Crossword clue: stick out or up

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

bulk 4 letters wn-def

the property resulting from being or relating to the greater in number of two parts; the main part

to give up or out. 50% similar → upgive

to shut up or out. 50% similar → beshut

to trace up or out. 50% similar → uptrace