Neglect nothing on a job (8)
I believe the answer is:
omission
'neglect' is the definition.
(I know that omission is a type of neglect)
'nothing on a job' is the wordplay.
'nothing on' becomes 'o' (I've seen this in other clues).
'a job' becomes 'mission' (a mission is a job or task).
'o'+'mission'='OMISSION'
(Other definitions for omission that I've seen before include "Something lacking" , "Oversight, piece of work neglected" , "lapse" , "Negligence" , "Mistake resulting from neglect" .)