Hefty slice (4)
I believe the answer is:
slab
'hefty slice' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for slab that I've seen before include "Broad, thick piece of wood, stone" , "Chunk of wood" , "24 tinnies [STRINE] < in a wooden hut [STRINE]" , "Flat broad piece as of stone" , "Thick flat piece of stone" .)