Trouble with worker on high-country tree (9)

I believe the answer is:

ailanthus

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'tree' is the definition.
(ailanthus is a kind of tree)

'trouble with worker on high-country' is the wordplay.
'trouble with' becomes 'ail' (synonyms. I am not sure about the 'with' bit.).
'worker' becomes 'ant' (worker is a type of ant).
'on' is a charade indicator (letters next to each other).
'high' becomes 'h' (abbreviation).
'country' becomes 'US' (United States).
'ail'+'ant'+'h'+'us'='AILANTHUS'

Can you help me to learn more?

(Other definitions for ailanthus that I've seen before include "Tree of Heaven; Thai Alnus (anag.)" , "ornamental tree" .)

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

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