How many letters does the top answer for “a small amount of solid food; a mouthful” have?

The most common answer is bite (4 letters).

Crossword clue: a small amount of solid food; a mouthful

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

bite 4 letters wn-def

to grip, cut off, or tear with or as if with the teeth or jaws

morsel 6 letters wn-def

a small amount of solid food; a mouthful

a small amount of liquid food 50% similar → sup, swallow