Unsubstantiated (7)
I believe the answer is:
tenuous
'unsubstantiated' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tenuous that I've seen before include "Very slight, with little substance or validity" , "Very thin in form, having little validity" , "Slender - insubstantial" , "Flimsy, thin" , "Very slight, insubstantial" .)