Detective Inspector had led corrupt swindle (6)
I believe the answer is:
diddle
'swindle' is the definition.
(synonyms)
'detective inspector had led corrupt' is the wordplay.
'detective inspector' becomes 'di'.
'had' becomes 'd' (I've seen this in other clues).
'corrupt' is an anagram indicator.
'led' with letters rearranged gives 'dle'.
'di'+'d'+'dle'='DIDDLE'
(Other definitions for diddle that I've seen before include "Con - do - lidded (anag)" , "Slangily cheat or swindle" , "Did, and led out to cheat" , "Fleece" , "Slang for cheat or swindle - nearly fiddle" .)