Energy supplier connected to star, perhaps (7)
I believe the answer is:
reactor
'energy supplier' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'connected to star perhaps' is the wordplay.
'connected to' becomes 're' (I can't explain this - if you can you should believe this answer much more).
'star perhaps' becomes 'actor' (star is a kind of actor).
're'+'actor'='REACTOR'
Can you help me to learn more?
(Other definitions for reactor that I've seen before include "Nuclear power station core" , "Producer of nuclear power" , "Apparatus for production of nuclear energy" , "See 3 Down" , "device that's energy-producing" .)