Official getting on with original sinner (5)
I believe the answer is:
reeve
'official' is the definition.
(I know that reeve is a type of official)
'on with original sinner' is the wordplay.
'on' becomes 're' ('on' can be mean 'with reference to').
'with' means one lot of letters go next to another.
'original sinner' becomes 'eve' (I've seen this in another clue).
're'+'eve'='REEVE'
'getting' acts as a link.
(Other definitions for reeve that I've seen before include "Comic actor" , "Former magistrate" , "Pass the end of a rope through the bailiff" , "[PILGRIM in the CANTERBURY TALES]" , "Chief magistrate of a district" .)