Cockney crane... (6)

I believe the answer is:

oyster

I'm a little stuck... Click here to teach me more about this clue!

'cockney crane' is the definition.
The definition and answer can be both animals as well as being singular nouns.
Maybe you can see an association between them that I can't see?

This is all the clue.

Can you help me to learn more?

(Other definitions for oyster that I've seen before include "Maybe grey" , "Shade of greyish white" , "Succulent bivalve, may bear a pearl" , "Shellfish - colour" , "Bivalve shellfish" .)

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

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