Heartlessly stabs hunks (6)
I believe the answer is:
pieces
'hunks' is the definition.
(hunk can mean a portion or lump)
'heartlessly stabs' is the wordplay.
'heartlessly' means to remove the middle letters.
'stabs' becomes 'pierces' (I've seen this before).
'pierces' with its middle removed is 'PIECES'.
(Other definitions for pieces that I've seen before include "Portions, parts" , "Bits, portions" , "Fragments" , "Bits < of sandwiches" , "Chessmen" .)