Will he cure plane sickness? (4,6)

I believe the answer is:

tree doctor

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'will he cure' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.

'plane sickness?' is the wordplay.
'plane' becomes 'tree' (plane tree is a type of tree).
'sickness?' becomes 'doctor' (I can't justify this - if you can you should give a lot more credence to this answer).
'tree'+'doctor'='TREE DOCTOR'

Can you help me to learn more?

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

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