Put forward as fact or as a basis for argument (7)
I believe the answer is:
posited
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">put forward as fact or as a basis for argument</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for posited that I've seen before include "Topside (anag.)" , "Suggested" , "Assumed" , "Advanced" , "Proposed as basis for argument" .)