Head off from Australian backwater, perhaps due to unpleasant odour? (4)

I believe the answer is:

reek

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'unpleasant odour?' is the definition.
(I know that unpleasant odour can be written as reek)

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for reek that I've seen before include "Does Croagh Patrick smell?" , "Smell of smoke in Kerry?" , "Smell like 12 Across" , "Smell bad" , "Whiff" .)

I've seen this clue in The Irish Times.

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