Isolated without lost member of staff (4)

I believe the answer is:

aide

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'member of staff' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps you can see a link between them that I don't see?

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for aide that I've seen before include "Leader's assistant" , "Personal assistant in the military" , "a help" , "Second" , "Somebody helping" .)

I've seen this clue in the Irish Times and the Irish Times (Crosaire).

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