Rascals having second thoughts after fraud (6)
I believe the answer is:
scamps
'rascals' is the definition.
('scamp' can be a synonym of 'rascal')
'second thoughts after fraud' is the wordplay.
'second thoughts' becomes 'ps' (as in P.S. in a letter).
'after' means one lot of letters go next to another.
'fraud' becomes 'scam' (scam is a kind of fraud).
'ps' put after 'scam' is 'SCAMPS'.
'having' acts as a link.
(Other definitions for scamps that I've seen before include "Mischevious young children" , "Naughty little rascals" , "'Rascals, imps (6)'" , "Little rascals, mischievous children" , "Scallywags" .)