Request for payment (7)
I believe the answer is:
invoice
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">request for payment</span>' is the definition.<br/ ><span class="explanation-format__explanation">(an invoice is sent to request payment)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for invoice that I've seen before include "Document detailing costs - ready to sing (7;2,5)" , "Statement of money to be paid" , "Statement for goods" , "Pollen holder" , "Give account" .)