Report Slug la Mode (8)

I believe the answer is:

bulletin

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'report' is the definition.
(bulletin is a kind of report)

'slug la mode' is the wordplay.
'slug' becomes 'bullet' (synonyms).
'la mode' becomes 'in' (I can't explain this - if you can you should give a lot more credence to this answer).
'bullet'+'in'='BULLETIN'

Can you help me to learn more?

(Other definitions for bulletin that I've seen before include "Newsflash" , "News programme" , "Official news item" , "News flash" , "Newsletter, report" .)

I've seen this clue in The Guardian.

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