Knockoffs (6)
I believe the answer is:
clones
'knockoffs' is the definition.
(I know this)
This is all the clue.
(Other definitions for clones that I've seen before include "Identical copies of cells" , "Organisms reproduced asexually" , "Propagates as with Dolly the sheep" , "Identical copies produced by genetic engineering" , "Genetically identical organisms derived from a single cell" .)