Cunning, in the main (4)

I believe the answer is:

deep

This clue is a double definition.

'cunning' is the first definition.
(thesaurus)

'main' is the second definition.
(thesaurus)

'in the' is the link.

(Other definitions for deep that I've seen before include "Heartfelt" , "dangerous for swimming?" , "Intense -- extreme" , "profoundly" , "Bottomless" .)

I've seen this clue in The Guardian and The Telegraph.

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