Better off, con (5)
I believe the answer is:
outdo
'better' is the definition.
(to outdo is to beat or do better than)
'off con' is the wordplay.
'off' becomes 'out' (both can mean wrong or inaccurate).
'con' becomes 'do' (to 'do' someone could be to con them).
'out'+'do'='OUTDO'
(Other definitions for outdo that I've seen before include "Eclipse" , "Perform better than surpass" , "Be better in performance (than another person)" , "Perform better than (someone)" , "Defeat" .)