Rotten Médoc, awfully pretentious (10)

I believe the answer is:

decomposed

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'rotten' is the definition.
(synonyms)

'medoc awfully pretentious' is the wordplay.
'awfully' indicates an anagram.
'pretentious' becomes 'posed' (I am not sure about this - if you are sure you should believe this answer much more).
'medoc' is an anagram of 'decom'.
'decom'+'posed'='DECOMPOSED'

Can you help me to learn more?

(Other definitions for decomposed that I've seen before include "broken down" , "Decayed" .)

I've seen this clue in The Times.

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