Popular organisation, though old-fashioned, is swamped (9)

I believe the answer is:

inundated

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'swamped' is the definition.
(synonyms)

'popular organisation though old-fashioned' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'organisation' becomes 'UN' (the United Nations is an organisation).
'though old-fashioned' becomes 'dated' (dated can mean old-fashioned. I am not sure about the 'though' bit.).
'in'+'un'+'dated'='INUNDATED'

'is' is the link.

Can you help me to learn more?

(Other definitions for inundated that I've seen before include "drowned" , "flooded" , "Deluged" .)

I've seen this clue in The Irish Times.

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