They’re known for the speed of their heavenly careers (7)

I believe the answer is:

meteors

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'careers' is the definition.
Although both the answer and definition are plural nouns, I can't understand how one could define the other.

I cannot understand how the remainder of the clue works.

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(Other definitions for meteors that I've seen before include "Shooting stars" , "Space fireballs" .)

I've seen this clue in the Evening Standard.

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