Endlessly hankering for pain relief (7)

I believe the answer is:

aspirin

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'pain relief' is the definition.
(I've seen this in another clue)

I can't explain the rest of the clue.

(Other definitions for aspirin that I've seen before include "Anodyne" , "Pain relief" , "headache cure" , "Common painkiller" , "Headache pill" .)

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

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