Put forward as fact or as a basis for argument (7)
I believe the answer is:
posited
'put forward as fact or as a basis for argument' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for posited that I've seen before include "Topside (anag.)" , "Suggested" , "Assumed" , "Advanced" , "Proposed as basis for argument" .)