At some stage note error also needs correction (6,2,5)
I believe the answer is:
sooner or later
'at some stage' is the definition.
'note error also needs correction' is the wordplay.
'needs correction' is an anagram indicator (I've seen 'needing correction' mean this (I've seen this in other clues)).
'note'+'error'+'also'='noteerroralso'
'noteerroralso' is an anagram of 'SOONER OR LATER'.
(Other definitions for sooner or later that I've seen before include "At some point" , "Inevitably" , "not on the dot" , "Errors (a lot) one corrected, eventually" , "offering alternative times" .)