Corrupt cheat shown up in tabloid (6)
I believe the answer is:
suborn
'corrupt' is the definition.
(suborning is a kind of corrupting)
'cheat shown up in tabloid' is the wordplay.
'cheat' becomes 'rob' (robbing is a kind of cheating).
'shown up' shows that the letters should be reversed in order.
'in' indicates putting letters inside.
'tabloid' becomes 'sun' (The Sun, UK newspaper).
'rob' written backwards gives 'bor'.
'bor' placed into 'sun' is 'SUBORN'.
(Other definitions for suborn that I've seen before include "Bribe (someone) to break law" , "Bribe to do wrong" , "Bribe (someone) to commit perjury" , "Induce by bribery to fail in one's duty" , "Induce (someone) to break the law" .)