Automaton, British in origin (5)
I believe the answer is:
robot
'automaton' is the definition.
('robot' can be a synonym of 'automaton')
'british in origin' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'in' indicates putting letters inside.
'origin' becomes 'root' ('root' can be a synonym of 'origin').
'b' going within 'root' is 'ROBOT'.
(Other definitions for robot that I've seen before include "Mechanical worker" , "Automated machine" , "Automatic machine" , "Man-made man - man-made machine" , "Humanoid machine" .)