Source of tofu (7)
(Other definitions for soybean that I've seen before include "Vegetable source of protein" , "American vegetable" .)
'source of tofu' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for soya that I've seen before include "Type of bean" , "It's used as a substitute for animal protein" , "Protein-yielding bean" , "nutritious bean" , "Animal-substitute (bean)" .)
(Other definitions for soy that I've seen before include "Chinese sauce" , "Oriental sauce" , "Sauce bean" , "Piquant eastern sauce" , "Dark salty sauce" .)