Crossword Genius

As cold as cold can be (8,4)

Ross

I believe the answer is:

absolute zero

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'cold can be' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

'as cold' is the wordplay.
'as' becomes 'absolute' (I can't explain this - if you can you should give a lot more credence to this answer).
'cold' becomes 'zero' (I've seen this before).
'absolute'+'zero'='ABSOLUTE ZERO'

'as' acts as a link.

Can you help me to learn more?

(Other definitions for absolute zero that I've seen before include "Minus 273 1/4 C approx." , "Coldest temperature" , "OK?" , "Lowest theoretical temperature" , "can't get lower than this" .)

I've seen this clue in The Irish Independent.
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