Corruption by some police repelled autocrat (8)
I believe the answer is:
dictator
'autocrat' is the definition.
(I've seen this before)
'corruption by some police repelled' is the wordplay.
'corruption' becomes 'rot' (rot can mean corruption or decay).
'by' becomes 'at' ().
'some police' becomes 'CID' (abbreviation for Criminal Investigation Department).
'repelled' says the letters should be written in reverse.
'rot'+'at'+'cid'='rotatcid'
'rotatcid' back-to-front is 'DICTATOR'.
(Other definitions for dictator that I've seen before include "One with absolute authority" , "ruthless leader" , "All-powerful ruler" , "Kind of ruler like Hitler or Franco" , "person in charge? Absolutely!" .)