Origin of larger machine (4)
I believe the answer is:
germ
'origin' is the definition.
(germ is a kind of origin)
'of larger machine' is the wordplay.
'of' says the answer is hidden in the clue.
'GERM' is hidden within 'larger machine'.
(Other definitions for germ that I've seen before include "Minute lifeform" , "Shoot" , "Small organism that spreads disease" , "Cause of disease" , "Micro-organism that causes disease" .)