Toyed with or succumbed to the temptation to swindle (7)
I believe the answer is:
fiddled
'toyed' is the definition.
('fiddle' can be a synonym of 'toy')
'or succumbed to the temptation to swindle' is the wordplay.
I cannot really see how this works, but
'swindle' could be 'fiddle' (I've seen this before) and 'fiddle' is found in the answer.
A single letter 'd' remains which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
'with' is the link.
Can you help me to learn more?
(Other definitions for fiddled that I've seen before include "Was corrupt" , "cheated" , "wasted time" , "What Nero did while Rome burned" .)