Bird with a speckled breast (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
thrush
(Other definitions for thrush that I've seen before include "Mouth fungus or songbird" , "Bird - fungal disease" , "Small bird - fungal mouth infection" , "Common songbird or throat infection" , "Songbird with brownish back and speckled breast" .)