Quote too much? Sounds like a minor mistake (9)
I believe the answer is:
oversight
'mistake' is the definition.
(oversight is a kind of mistake)
'quote too much? sounds like a minor' is the wordplay.
I cannot quite understand how this works, but
'too much?' could be 'over' (over can mean to too great an extent) and 'over' is present in the answer.
The remaining letters 'sight' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for oversight that I've seen before include "Mistake resulting from inattention" , "Failure to notice something" , "Failure to notice - supervision" , "Supervisor's charged with this" , "what supervisor has" .)