Deficient punctuation unprecedented in bulletin (10)
I believe the answer is:
communique
'bulletin' is the definition.
(I've seen this in another clue)
'deficient punctuation unprecedented' is the wordplay.
'deficient' means to remove the last letter.
'punctuation' becomes 'comma' (comma is a kind of punctuation).
'unprecedented' becomes 'unique' (something unprecedented is unique).
'comma' with its final letter removed is 'comm'.
'comm'+'unique'='COMMUNIQUE'
'in' is the link.
(Other definitions for communique that I've seen before include "Official statement" , "Source of news" , "Official announcement" .)