Remains of two extremities (4-3)

I believe the answer is:

tail-end

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'remains' is the definition.
The answer and definition can be both body parts as well as being singular nouns.
Maybe you can see an association between them that I can't see?

'two extremities' is the wordplay.
'two extremities' means two replacements for 'extremity'.
'extremity' becomes 'tail' (extremity on an animal's body).
'extremity' becomes 'end' (end is a kind of extremity).
'tail'+'end'='TAIL-END'

'of' acts as a link.

Can you help me to learn more?

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

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