What a meter may require every half mile? (6)

I believe the answer is:

needle

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'what a meter may require' is the definition.
I can't judge whether this definition defines the answer.

'every half mile?' is the wordplay.
'every' becomes 'need' (I can't justify this - if you can you should believe this answer much more).
'half' means to take half the letters.
'mile' cut in half is 'le'.
'need'+'le'='NEEDLE'

Can you help me to learn more?

(Other definitions for needle that I've seen before include "It points" , "Hostility - annoy - sewing tool" , "Unnecessary" , "Implement for knitting and sewing" , "Persistently annoy" .)

I've seen this clue in the Evening Standard.

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