Electrical device (9)
(Other definitions for appliance that I've seen before include "Device used for a particular purpose" , "implement" , "Fire engine" , "Piece of kit" , "Useful device, gadget" .)
'electrical device' is the definition.
(battery is a kind of electrical device)
This is all the clue.
(Other definitions for battery that I've seen before include "Device that converts chemical energy into electrical energy" , "One may be charged" , "Infliction of violence" , "criminal offence" , "Equipment for war" .)