Contemptible sort has denied beginning long con (7)
I believe the answer is:
swindle
'con' is the definition.
(both can mean a fraud or scam)
'contemptible sort has denied beginning long' is the wordplay.
'contemptible sort' becomes 'swine' (I've seen this in another clue).
'has' indicates putting letters inside.
'beginning' indicates taking the first letters.
'long' becomes 'l'.
The first letter of 'denied' is 'd'.
'd'+'l'='dl'
'swine' going around 'dl' is 'SWINDLE'.
(Other definitions for swindle that I've seen before include "fleece" , "Fraudulent action" , "Take" , "Diddle, sting, twist" , "Cheat (out of money)" .)