Expense (4)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">expense</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that expense can be written as cost)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for cost that I've seen before include "Fee" , "Amount to pay" , "estimate price" , "Amount required as payment" , "Charge" .)