Irish water in sunless bog (5)

I believe the answer is:

lough

'irish water' is the definition.
(Irish term for a loch or lake)

I cannot understand how the rest of the clue works.

(Other definitions for lough that I've seen before include "Irish word for lake" , "An Irish lake or arm of the sea" , "Example of liquidity" , "Irish loch" , "Body of water" .)

I've seen this clue in The Guardian.

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