Scales up? (5)
I believe the answer is:
'scales up?' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for libra that I've seen before include "Someone born between September 23 and October 22" , "The Scales in astrology" , "Person born under Scales sign" , "Seventh sign of the Zodiac" , "Constellation near Virgo" .)