Small fund for incidental expenses (5,4)
I believe the answer is:
petty cash
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">small fund for incidental expenses</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 petty cash that I've seen before include "money kept for small expenses" , "Money kept in office for small payments - it's trivial" , "Small amounts of money set aside for insignificant payments" , "Small fund for minor expenses" , "Money for small day-to-day expenses" .)