Chirpy sort almost putting on ceremonial dress (5)
I believe the answer is:
robin
'chirpy sort' is the definition.
(bird which chirps)
'almost putting on ceremonial dress' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'putting on ceremonial dress' becomes 'robing' (dressing in ceremonial robes).
'robing' with its last letter taken off is 'ROBIN'.
(Other definitions for robin that I've seen before include "Garden bird" , "Bird - boy's name" , "Small brown thrush" , "Batman and --" , "Bird - one in Lincoln green?" .)