Get firmly established and start eating (3,2)

I believe the answer is:

dig in

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'start eating' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

(Other definitions for dig in that I've seen before include "Begin eating (informal)" , "Begin eating heartily" , "Start to scoff" , "Enjoy the food" , "protect himself" .)

I've seen this clue in the Evening Standard.

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