Swindle rascal detailed (4)
I believe the answer is:
scam
'swindle' is the definition.
(scam is a kind of swindle)
'rascal detailed' is the wordplay.
'rascal' becomes 'scamp' ('scamp' can be a synonym of 'rascal').
'detailed' means to remove the last letter (the word must be end-less or 'de-tailed').
'scamp' with its last letter removed is 'SCAM'.
(Other definitions for scam that I've seen before include "A modern kind of swindle" , "Fraudulent trick or swindle" , "Dubious operation" , "A slangy swindle or fraud" , "Swindle, fraud (colloq.)" .)