Show an inclination to be a cad (4)
I believe the answer is:
heel
'cad' is the definition.
(synonyms)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for heel that I've seen before include "3's weak point" , "that may be Cuban" , "A cad and a bounder!" , "Crusty end of a loaf" , "swine" .)