Cork tip (4)

I believe the answer is:

bung

I believe this clue is a double definition.

'cork' is the first definition.
(I have seen 'Large cork' mean 'bung' so perhaps 'cork' could also mean 'bung')

'tip' is the second definition.
('bung' can be a synonym of 'tip')

(Other definitions for bung that I've seen before include "could be a corker" , "Spigot or cork" , "Tip, bribe (sl.)" , "Bribe; throw" , "illegal incentive" .)

I've seen this clue in The Telegraph.

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