More corrupt detective runs bank (7)
I believe the answer is:
dirtier
'more corrupt' is the definition.
('dirty' can be similar in meaning to 'corrupt')
'detective runs bank' is the wordplay.
'detective' becomes 'di' (Detective Inspector abbreviation).
'runs' becomes 'r' (cricket abbreviation).
'bank' becomes 'tier' (I've seen this before).
'di'+'r'+'tier'='DIRTIER'
(Other definitions for dirtier that I've seen before include "More filthy" , "More grubby" , "Filthier" , "cleaner? The opposite" , "Less clean" .)