Invention something coming from ox hide (3,3)
I believe the answer is:
lie low
'hide' is the definition.
(lying low is a kind of hiding)
'invention something coming from ox' is the wordplay.
'invention' becomes 'lie'.
'something coming from ox' becomes 'low' (term for a mooing sound).
'lie'+'low'='LIE LOW'
(Other definitions for lie low that I've seen before include "Avoid attracting notice" , "Use bottom bunk, perhaps" , "take cover" , "Be inconspicuous - in horizontal position?" , "Go into hiding" .)