Commercial with an electrical connection (4)
I believe the answer is:
plug
'commercial' is the definition.
(I've seen this in another clue)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for plug that I've seen before include "See 19" , "Favourable mention" , "Promote" , "Seal" , "Stuff" .)