Against swindle (3)
I believe the answer is:
con
I believe this is a double definition.
'against' is the first definition.
(as in pros and cons, for and against)
'swindle' is the second definition.
(I know that swindle can be written as con)
(Other definitions for con that I've seen before include "Study - trick" , "This man is a swindler" , "Deceive; disadvantage" , "Deceive; convict (colloq.)" , "Swindle in draconian way" .)