Suffering from internal Sumatran disorder (6)

I believe the answer is:

trauma

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'disorder' is the definition.
(trauma is a kind of health problem)

I don't understand the rest of the clue.

(Other definitions for trauma that I've seen before include "Shock with long-lasting effects" , "Severe shock, injury" , "Wound - emotional shock" , "Physical injury (medical)" , "Lasting shock or disturbance" .)

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

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