Overturn unexpected result (5)
I believe the answer is:
upset
I believe this clue is a double definition.
'overturn' is the first definition.
('upset' can be a synonym of 'overturn')
'unexpected result' is the second definition.
(I've seen this before)
(Other definitions for upset that I've seen before include "Distressed - surprise" , "Out of sorts" , "Trouble" , "bug" , "emotional" .)