Circuits with energy failing (5)
I believe the answer is:
lapse
'failing' is the definition.
(a moral failing)
'circuits with energy' is the wordplay.
'circuits' becomes 'laps' ('lap' can be a synonym of 'circuit').
'with' is a charade indicator (letters next to each other).
'energy' becomes 'e' (physics symbol as in E=mc2).
'laps'+'e'='LAPSE'
(Other definitions for lapse that I've seen before include "Run out" , "Slip back" , "Pass into disuse" , "Pleas about omission" , "falling away" .)