Dog with a blue-black tongue (4)
I believe the answer is:
chow
'dog with a blue-black tongue' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for chow that I've seen before include "[HOUND]" , "Nosh" , "Long-haired Chinese dog or slangy food" , "Dog (from China?)" , "breakfast?" .)