Source of tallow (4)
I believe the answer is:
suet
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">source of tallow</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for suet that I've seen before include "Hard white fat on sheep's kidneys" , "Fatty stuff used in cooking" , "Edible fat used in cooking" , "Thin pancake" , "Edible animal fat" .)