Cold-hearted hustler's new plan (8)

I believe the answer is:

ruthless

I'm a little stuck... Click here to teach me more about this clue!

'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" .)

I've seen this clue in the Sydney Morning Herald.

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