First sign of the zodiac (5)
I believe the answer is:
aries
'first sign of the zodiac' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for aries that I've seen before include "Zodiac ram" , "A sign from Heaven" , "House" , "Zodiacal sign also known as the Ram" , "Ram star sign" .)