Backer (7)
I believe the answer is:
sponsor
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">backer</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 sponsor that I've seen before include "One pledging money" , "Godparent; financial supporter" , "A godfather or patron" , "Provide finance for" , "Back financially" .)