Teach about swindle (5)
I believe the answer is:
cheat
'swindle' is the definition.
('cheat' can be a synonym of 'swindle')
'teach about' is the wordplay.
'about' is an anagram indicator.
'teach' is an anagram of 'CHEAT'.
(Other definitions for cheat that I've seen before include "Skin" , "Fool" , "Swindler - crib" , "Hoodwink" , "One dealing dishonestly" .)