Frequent complainant upset cabby snorting lines (7)
I believe the answer is:
crybaby
'frequent complainant' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'upset cabby snorting lines' is the wordplay.
'upset' indicates an anagram.
'snorting' indicates putting letters inside (snort can mean to ingest through the nose).
'lines' becomes 'ry' (abbreviation for railway).
'cabby' anagrammed gives 'cbaby'.
'cbaby' going around 'ry' is 'CRYBABY'.
Can you help me to learn more?
(Other definitions for crybaby that I've seen before include "Person readily shedding tears" , "Person too easily reduced to tears" , "One prone to tears" , "(Very young?) weeper" , "One sheds tears easily" .)