Ill-fated prophet and a crass criminal (9)
I believe the answer is:
cassandra
'ill-fated prophet' is the definition.
'cassandra' can be an answer for 'prophet' (I have seen 'Prophet of doom' mean 'cassandra' so perhaps 'prophet' could also mean 'cassandra'). I'm not certain of the 'ill-fated' bit.
'and a crass criminal' is the wordplay.
'criminal' indicates an anagram.
'and'+'a'+'crass'='andacrass'
'andacrass' anagrammed gives 'CASSANDRA'.
Can you help me to learn more?
(Other definitions for cassandra that I've seen before include "Person who prophesies disaster, after Greek legend (9)" , "Gloomy Greek prophetess or one given to pessimistic prophesy" , "Prophetess of doom" , "Unheeded prophetess" , "forecaster" .)