What's due (4)
I believe the answer is:
debt
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">what's due</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 debt that I've seen before include "Amount owed" , "Financial problem?" , "Something owed" , "Sum of money that's owed" , "outstanding" .)