Plug (4)
'plug' is the definition.
(plug can mean an advertisement or promotional item)
This is all the clue.
(Other definitions for advertisement that I've seen before include "Notice - commercial" , "Bill" , "plug" , "Commercial promotion" , "Publicity announcement" .)
'plug' is the definition.
(I know that stopper is a kind of plug)
This is the entire clue.
(Other definitions for stopper that I've seen before include "Plug for a bottle" , "One who checks" , "Maybe cork" , "Bung" , "Perhaps cork" .)
'plug' is the definition.
(stop can mean to plug a gap)
This is all the clue.
(Other definitions for stop that I've seen before include "Close < finish" , "Put off for ever" , "oboe, perhaps" , "Standstill" , "Cease; organ voice" .)
'plug' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for clog that I've seen before include "Block up - type of shoe" , "Shoe with a thick wooden sole" , "Obstruct the wooden shoe" , "Block with wooden-soled shoe?" , "Footwear - hamper" .)