Came after heartless ex-con who took legal action (6)
I believe the answer is:
ensued
'came after heartless ex-con who took legal action' is the definition.
'ensued' can be an answer for 'came after' (I've seen this before). I'm unsure of the remainder of the definition.
'came after heartless ex-con' is the wordplay.
'came after' becomes 'entered upon' (entering upon is a kind of coming after).
'heartless' suggests removing the centre.
'ex con' becomes 'sued' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'enteredupon' with its middle removed is 'en'.
'en'+'sued'='ENSUED'
Can you help me to learn more?
(Other definitions for ensued that I've seen before include "Befell" , "Followed as a consequence" , "Resulted, followed" , "Happened in consequence" , "Happened afterwards or as a result" .)