Unfounded (8)
I believe the answer is:
baseless
'unfounded' is the definition.
(I know that unfounded can be written as baseless)
This is all the clue.
(Other definitions for baseless that I've seen before include "Idle" , "lacking support" , "like a bed with just a mattress?" , "Without foundation, as rumours may be" , "Without foundation, unsupported" .)