Harbinger of spring (5)
I believe the answer is:
robin
'harbinger of spring' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for robin that I've seen before include "Small brown and red bird" , "Hood, possibly" , "Bird; Batman's aide" , ". . . . . Hood was a medieval outlaw" , "Red and brown songbird" .)