Vulgar -- and a notable stinker! (4,6)
I believe the answer is:
blue cheese
'stinker' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'vulgar and a notable' is the wordplay.
'vulgar' becomes 'blue' (I've seen this before).
'and' says to put letters next to each other.
'a notable' becomes 'cheese' (I can't justify this - if you can you should give a lot more credence to this answer).
'blue'+'cheese'='BLUE CHEESE'
Can you help me to learn more?
(Other definitions for blue cheese that I've seen before include "Eg, Stilton" , "Stilton, perhaps" , "Dairy product" , "Danish for example" , "Stilton, for instance" .)