Answer: discredit

AnswerCrossword Clue
DISCREDIT

Show to be untrustworthy

DISCREDIT

Cast doubt on

DISCREDIT

Defame

DISCREDIT
Prove false
DISCREDIT
Doubt.
DISCREDITCast doubt on.
DISCREDITRefuse to believe
DISCREDITDisgrace
DISCREDITDrag through the mud
DISCREDITImpugn