Dogger’s crude? (5,3,3)

I believe the answer is:

north sea oil

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'dogger's crude?' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.

'dogger's crude?' is the wordplay.
'dogger' becomes 'northsea' (I can't explain this - if you can you should believe this answer much more).
'crude?' becomes 'oil' (crude oil).
'northsea'+'oil'='NORTH SEA OIL'

Can you help me to learn more?

(Other definitions for north sea oil that I've seen before include "Fuel obtained off British shores" , "Deep resource" .)

I've seen this clue in The Times.

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