A once wild area of the world (5)

I believe the answer is:

ocean

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'area of the world' is the definition.
'ocean' can be an answer for 'world' (thesaurus). I am not certain of the 'area of the' bit.

'a once wild' is the wordplay.
'wild' indicates anagramming the letters.
'a'+'once'='aonce'
'aonce' with letters rearranged gives 'OCEAN'.

Can you help me to learn more?

(Other definitions for ocean that I've seen before include "eg Arctic" , "Huge sea" , "Pacific, for example" , "Great sea" , "Big sea" .)

I've seen this clue in The Globe and Mail.

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