Being in a boggy area spoils a hotel (5)

I believe the answer is:

marsh

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'being in a boggy area' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.

'spoils a hotel' is the wordplay.
'spoils' becomes 'mars' ('mar' can be a synonym of 'spoil').
'a hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'mars'+'h'='MARSH'

Can you help me to learn more?

(Other definitions for marsh that I've seen before include "Quagmire" , "Fen" , "Swampy ground" , "eg Romney" , "Waterlogged land" .)

I've seen this clue in the Evening Standard.

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