Advertise electrical accessory (4)
I believe the answer is:
plug
I believe this clue is a double definition.
'advertise' is the first definition.
(plugging is a kind of advertizing)
'electrical accessory' is the second definition.
(Other definitions for plug that I've seen before include "Stuff" , "Cork" , "Wad of tobacco and electrical accessory" , "Stop - advertising" , "Shoot" .)