Awfully troublesome that rum has gone off - it's out of date (8)

I believe the answer is:

obsolete

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'out of date' is the definition.
(I've seen this before)

I don't understand the rest of the clue.

(Other definitions for obsolete that I've seen before include "No longer useful" , "No longer produced or used" , "Dead" , "Outdated" , "No longer current" .)

I've seen this clue in The Irish Times.

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