Sum of money (6)
I believe the answer is:
amount
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sum of money</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for amount that I've seen before include "A quantity or total of anything" , "Quantity, sum" , "Size" , "Total or extent" , "Sum of money" .)