Bean protein (4)
I believe the answer is:
soya
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">bean protein</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for soya that I've seen before include "Plant producing beans" , "Protein derived from oriental beans" , "Bean protein" , "It's used as a substitute for animal protein" , "Asian bean yielding edible oil and flour" .)