Embryo (6)
I believe the answer is:
foetus
'embryo' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for foetus that I've seen before include "Human embryo more than six weeks after conception" , "issue" , "Unborn child" , "Developed embryo in the womb" , "Developed mammalian embryo" .)