Good eggs repelled cheat (5)
I believe the answer is:
sting
'cheat' is the definition.
(sting can mean to cheat or trick)
'good eggs repelled' is the wordplay.
'good' becomes 'g' (abbreviation).
'eggs' becomes 'nits' (nit is a kind of egg).
'repelled' says the letters should be written backwards.
'g'+'nits'='gnits'
'gnits' backwards is 'STING'.
(Other definitions for sting that I've seen before include "Con: leader singer of Police" , "piece of deception" , "fleece?" , "viz. Gordon Sumner" , "Tingle sharply" .)