Terrific new energy charges electrical device (9)
I believe the answer is:
rectifier
'electrical device' is the definition.
(rectifier is a kind of electrical device)
'terrific new energy charges' is the wordplay.
'new' indicates anagramming the letters.
'energy' becomes 'e' (physics symbol as in E=mc2).
'charges' indicates putting letters inside (charge can mean to charge into something).
'terrific' anagrammed gives 'rectifir'.
'rectifir' placed around 'e' is 'RECTIFIER'.
(Other definitions for rectifier that I've seen before include "which allows smooth flow" , "Device such as a diode" , "Electrical device converting AC to DC" , "I provide a remedy" , "Device for changing AC to DC current" .)