That filled up as an occupation? (5)

I believe the answer is:

space

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'occupation?' is the definition.
The answer and definition can be both groups as well as being singular nouns.
Maybe there's a link between them I don't understand?

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for space that I've seen before include "-- Capsule; -- bar" , "Cosmos" , "Interstellar region" , "Unfilled region" , "Room for capes" .)

I've seen this clue in the Evening Standard.

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