Angelo wrong? George is abiding? (7)

I believe the answer is:

agelong

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'abiding?' is the definition.
Both the answer and definition are adjectives. Maybe they are linked in a way I don't understand?

'angelo wrong? george' is the wordplay.
'wrong?' indicates anagramming the letters (I've seen 'wrong' mean this).
'george' becomes 'g'.
'angelo' anagrammed gives 'agelon'.
'agelon'+'g'='AGELONG'

'is' acts as a link.

Can you help me to learn more?

(Other definitions for agelong that I've seen before include "Having existed for many a year" , "over a period of many years" , "Seeming to have always been so" , "Lasting much time; lag gone (anag.)" , "Almost endless" .)

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

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