Spoken error upsetting fool, he being corrected (4,2,3,6)
I believe the answer is:
slip of the tongue
'spoken error' is the definition.
(error made when speaking)
'upsetting fool he being corrected' is the wordplay.
'being corrected' is an anagram indicator.
'upsetting'+'fool'+'he'='upsettingfoolhe'
'upsettingfoolhe' is an anagram of 'SLIP OF THE TONGUE'.
(Other definitions for slip of the tongue that I've seen before include "mistake one hears" , "Error in words" , "vocal error" , "a small error" .)