Greek caterin' is a form of extortion! (12)
I believe the answer is:
racketeering
'form of extortion' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe there's a link between them I don't understand?
'greek caterin'' is the wordplay.
'greek caterin' can be anagrammed to 'RACKETEERING'.
But, I'm not clear how this is indicated.
'is a' acts as a link.
Can you help me to learn more?
(Other definitions for racketeering that I've seen before include "Dealing fraudulently" , "Fraudulent dealing" .)