Cold-hearted hustler's new plan (8)
I believe the answer is:
ruthless
'cold-hearted' is the definition.
(thesaurus)
'hustler's new plan' is the wordplay.
'hustler's' anagrams to 'RUTHLESS'.
Though, I'm not clear how the anagram is indicated.
Can you help me to learn more?
(Other definitions for ruthless that I've seen before include "Without mercy or pity" , "Harsh" , "Without pity, merciless" , "Brutal" , "Without pity or compassion" .)