Small chicken breed (6)
I believe the answer is:
bantam
'small chicken breed' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for bantam that I've seen before include "Dwarf variety of domestic fowl" , "weight of a pug" , "Little clucker" , "Boxing weight or domestic fowl" , "Domestic fowl; small fighter" .)