Extremely disagreeable commercials, each for foreign waters (4,3)

I believe the answer is:

dead sea

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'foreign waters' is the definition.
The definition suggests a singular noun which matches the answer.

'extremely disagreeable commercials each' is the wordplay.
'extremely' says to hollow out the word (remove centre letters).
'commercials' becomes 'ads' (I've seen this before).
'each' becomes 'ea'.
'disagreeable' with its centre removed is 'de'.
'de'+'ads'+'ea'='DEAD SEA'

'for' is the link.

Can you help me to learn more?

(Other definitions for dead sea that I've seen before include "large salt lake" , "Didn't win; TV series" , "Salt lake fed by the Jordan river" , "Lowest lake in the world" , "Disappearing lake" .)

I've seen this clue in the Sydney Morning Herald.

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