Innocent mistake concerning vision (9)
I believe the answer is:
oversight
'innocent mistake' is the definition.
(I've seen this before)
'concerning vision' is the wordplay.
'concerning' becomes 'over' (both can mean relating to).
'vision' becomes 'sight' (synonyms).
'over'+'sight'='OVERSIGHT'
(Other definitions for oversight that I've seen before include "Management" , "what supervisor has" , "Supervisor's charged with this" , "Neglect" , "Got shiver due to forgetfulness" .)