Get stuck into a hefty slice (5)

I believe the answer is:

wedge

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

I cannot understand how the rest of the clue works.

(Other definitions for wedge that I've seen before include "Device eg to keep door open" , "Splitting device" , "Piece of wood thick at one end, thin at other" , "Chock" , "Jam" .)

I've seen this clue in the Evening Standard.

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