Land it in case of grey matter (7)

I believe the answer is:

britain

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'land' is the definition.
(Britain is an example)

'it in case of grey matter' is the wordplay.
'in' means one lot of letters goes inside another.
'case of grey matter' becomes 'brain' (I am not sure about this - if you are sure you should believe this answer much more).
'it' placed within 'brain' is 'BRITAIN'.

Can you help me to learn more?

(Other definitions for britain that I've seen before include "UK's largest island" , "State" , "England, Scotland, Wales and Northern Ireland" , "Island north of France" , "Main UK island" .)

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

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