Android ran on batteries of tungsten to begin with (5)
I believe the answer is:
robot
'android' is the definition.
(I've seen this in another clue)
'ran on batteries of tungsten to begin with' is the wordplay.
'to begin with' suggests taking the first letters.
The initial letters of 'ran on batteries of tungsten' is 'ROBOT'.
(Other definitions for robot that I've seen before include "Factory worker, perhaps" , "Soulless worker" , "Automation" , "Computer-driven entity" , "Unpaid worker" .)