Error in commentator’s position on left (9)
I believe the answer is:
oversight
'error' is the definition.
(oversight is a kind of error)
'commentator's position on left' is the wordplay.
'commentator's position' becomes 'sight' (I can't explain this - if you can you should give a lot more credence to this answer).
'on' means one lot of letters go next to another.
'left' becomes 'over' (I've seen this before).
'sight' after 'over' is 'OVERSIGHT'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for oversight that I've seen before include "Management" , "Innocent mistake" , "Supervision - omission" , "Neglect" , "error" .)