Prove to be false (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
rebut
'prove to be false' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for rebut that I've seen before include "explode" , "Prove the claim wrong" , "Prove to be false or incorrect" , "Contradict or disprove" , "Overturn" .)