Money order (6)
I believe the answer is:
cheque
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">money order</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 cheque that I've seen before include "A payment order form" , "means of transferring funds" , "Paper payment" , "Method of payment" , "Means of payment" .)