A girl they shifted some distance away (5,4)

I believe the answer is:

light year

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'some distance away' is the definition.
I can't judge whether this defines the answer.

'a girl they shifted' is the wordplay.
'shifted' is an anagram indicator.
'a'+'girl'+'they'='agirlthey'
'agirlthey' with letters rearranged gives 'LIGHT-YEAR'.

Can you help me to learn more?

(Other definitions for light year that I've seen before include "About 5.88 trillion miles" , "Long unit of distance" , "astronomically large" , "0.3066 parsecs" , "that is way beyond anyone's reach!" .)

I've seen this clue in The Guardian.

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