Upset, it is clear, by the run-out (8)
I believe the answer is:
overturn
'upset' is the definition.
(I know that upset can be written as overturn)
'clear by the run-out' is the wordplay.
'clear' becomes 'overt' (both can mean apparent or obvious).
'by' is a charade indicator (letters next to each other).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'run' anagrammed gives 'urn'.
'overt'+'urn'='OVERTURN'
'it is' acts as a link.
(Other definitions for overturn that I've seen before include "Reverse or capsize" , "tip" , "Capsize - invalidate" , "Reverse, rescind," , "Reverse; upend" .)