Scales calibrated to some extent (5)

I believe the answer is:

libra

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

'calibrated to some extent' is the wordplay.
'to some extent' says the answer is hidden in the clue.
'LIBRA' is hidden in the letters of 'calibrated'.

(Other definitions for libra that I've seen before include "Balance constellation" , "House" , "Scales constellation" , "The Scales in astrology" , "stars" .)

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app