Swindles causing fools to lose heart (4)
I believe the answer is:
does
'swindles' is the definition.
(UK word meaning to cheat)
'fools to lose heart' is the wordplay.
'fools' becomes 'dopes' (I've seen this before).
'to lose heart' suggests removing the centre (I've seen 'losing heart' mean this).
'dopes' with its centre removed is 'DOES'.
'causing' is the link.
(Other definitions for does that I've seen before include "Executes - female deer" , "herbivores" , "Suffices" , "some females" , "some antelopes or deer, perhaps" .)