Verifiable statement (4)
I believe the answer is:
fact
'verifiable statement' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for fact that I've seen before include "True item; reality" , "Indisputable thing" , "Something indisputable" , "Piece of information known to be true" , "An indisputable truth" .)