No Brie? Unlucky! (4,6)

I believe the answer is:

hard cheese

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'no brie? unlucky' is the definition.
I can't tell whether this defines the answer.

'no brie?' is the wordplay.
'no' becomes 'hard' (I can't justify this - if you can you should believe this answer much more).
'brie?' becomes 'cheese' (brie is a kind of cheese).
'hard'+'cheese'='HARD CHEESE'

Can you help me to learn more?

(Other definitions for hard cheese that I've seen before include "Bad luck! (Grate it!)" , "Eighteen [EMMENTAL], for instance" , "Tough luck (informal)" , "Expression of sympathy" , "Leicester" .)

I've seen this clue in The Times and The Sunday Times.

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