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