Quantity (of money) (3)
I believe the answer is:
sum
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">quantity of money</span>' is the definition.<br/ ><span class="explanation-format__explanation">(as in a cash sum)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for sum that I've seen before include "pupils find it a problem" , "Amount, of money say" , "See 25" , "Quantity of money" , "Whole" .)