A popular calling (8)
I believe the answer is:
nickname
'a popular calling' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
This is the entire clue.
Can you help me to learn more?
(Other definitions for nickname that I've seen before include "tag" , "Friendly appellation by which person is known" , "A handle" , "Cognomen" , "Not the one one is christened with" .)