Heartless men regularly turn in wizards (7)
I believe the answer is:
maestri
'wizards' is the definition.
The definition and answer can be both people as well as being plural nouns.
Perhaps there's a link between them I don't understand?
'heartless men regularly turn in' is the wordplay.
'heartless men' becomes 'maes' (I can't justify this - if you can you should give a lot more credence to this answer).
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'turn'+'in'='turnin'
The alternating letters of 'turnin' are 'tri'.
'maes'+'tri'='MAESTRI'
Can you help me to learn more?
(Other definitions for maestri that I've seen before include "masters" , "Top musicians" , "great musicians" , "Distinguished musicians" , "Eminent musical conductors" .)