Passionate about climbing headland to get the bush? (10)

I believe the answer is:

wilderness

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'the bush?' is the definition.
(thesaurus)

'passionate about climbing headland' is the wordplay.
'passionate about climbing' becomes 'wilder' (I can't explain this - if you can you should believe this answer much more).
'headland' becomes 'ness' (I've seen this before).
'wilder'+'ness'='WILDERNESS'

'to get' is the link.

Can you help me to learn more?

(Other definitions for wilderness that I've seen before include "for a time unrecognised" , "Inhospitable region" .)

I've seen this clue in The Times.

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