Tree gets angry over oral abscesses (8)

I believe the answer is:

gumboils

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'oral abscesses' is the definition.

'tree gets angry' is the wordplay.
'tree' becomes 'gum tree' (gum is a kind of tree).
'gets angry' becomes 'boils'.
'gum'+'boils'='GUMBOILS'

'over' acts as a link.
This may not be right. It may belong to another bit of the clue.

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

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