One may be powerless without it (11)
I believe the answer is:
electricity
'it' is the definition.
The definition suggests a singular noun which matches the answer.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for electricity that I've seen before include "One form of energy" , "Domestic energy supply" , "Current supplier" , "Energy associated with charged particles" , "Energy from movement of charged particles" .)