Republican at heart of fraud? Get away! (5)
I believe the answer is:
scram
'get away' is the definition.
(I've seen this before)
'republican at heart of fraud?' is the wordplay.
'republican' becomes 'R' (abbreviation in US politics).
'at heart of' is an insertion indicator.
'fraud?' becomes 'scam' (scam is a kind of fraud).
'r' inserted inside 'scam' is 'SCRAM'.
(Other definitions for scram that I've seen before include "Skedaddle!" , "Slangy order to go away, beat it" , "Bolt" , "Clear off!" , "Make oneself scarce" .)