Develop land labelled 'AN', that's the only important thing (2-3,3,3-3)

I believe the answer is:

be-all and end-all

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'the only important thing' is the definition.
The definition suggests a singular noun which matches the answer.

'develop land labelled an' is the wordplay.
'develop' is an anagram indicator.
'land'+'labelled'+'an'='landlabelledan'
'landlabelledan' anagrammed gives 'BE-ALL AND END-ALL'.

'that's' is the link.

Can you help me to learn more?

(Another definition for be-all and end-all that I've seen is " Supreme issue (2-3,3,3-3)".)

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

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