Scales requiring a degree of calibration (5)

I believe the answer is:

libra

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'scales' is the definition.
(I have seen 'The Scales' mean 'libra' so perhaps 'scales' could also mean 'libra')

'of calibration' is the wordplay.
'of' indicates the answer is hidden within the clue.
'LIBRA' is hidden in the letters of 'calibration'.

'requiring a degree' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.

Can you help me to learn more?

(Other definitions for libra that I've seen before include "Zodiacal sign" , "House" , "The Scales in astrology" , "Constellation near Virgo" , "Person born under Scales sign" .)

I've seen this clue in the Evening Standard.

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