Discharge energy (4)

I believe the answer is:

fire

I believe this is a double definition.

'discharge' is the first definition.
('fire' can be a synonym of 'discharge')

'energy' is the second definition.
(thesaurus)

(Other definitions for fire that I've seen before include "There's no smoke without it" , "Weaponry" , "Shoot; sack" , "Ready, aim . . . ." , "Sack; conflagration" .)

I've seen this clue in The Telegraph.

Want a hint initially instead of a full solution? Install my app