Shown to be false (8)
(Other definitions for debunked that I've seen before include "Showed to be false or incorrect" , "Cut down to size!" , "Showed up as false or exaggerated" , "ruined reputation?" , "Uncovered pretentious or false claims and ideas" .)
(Other definitions for belied that I've seen before include "Contradicted or disproved" , "Contradicted, negated" , "Failed to confirm, or gave false idea of" .)
'shown to be false' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for disproven that I've seen before include "shown to be false" , "Demonstrated to be false" .)