Stop promotion (4)

I believe the answer is:

plug

I believe this is a double definition.

'stop' is the first definition.
(plug is a kind of stop)

'promotion' is the second definition.
(plug is a kind of promotion)

(Other definitions for plug that I've seen before include "Good word" , "Wad, of tobacco say" , "It fits into electric socket" , "Device put into socket" , "Stopper - connector" .)

I've seen this clue in The Guardian.

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