Crossword Genius

What separates Grimsby from The Hague or Athens, bizarrely (5,3)

Ross

I believe the answer is:

north sea

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'what separates grimsby from the hague' is the definition.
I can't tell whether this definition defines the answer.

'or athens bizarrely' is the wordplay.
'bizarrely' indicates an anagram.
'or'+'athens'='orathens'
'orathens' is an anagram of 'NORTH SEA'.

Can you help me to learn more?

(Other definitions for north sea that I've seen before include "(Formerly) German Ocean" , "Water to east of UK" , "Source of UK's oil/gas" , "Water beside UK" , "UK source of natural gas" .)

I've seen this clue in The Independent.
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