One quitting from GP circuit with sulky expression (7)
I believe the answer is:
dropout
'one quitting' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'gp circuit with sulky expression' is the wordplay.
'gp' becomes 'dr' (general practitioner).
'circuit' becomes 'o'.
'with' means one lot of letters go next to another.
'sulky expression' becomes 'pout' (I've seen this before).
'dr'+'o'+'pout'='DROPOUT'
'from' acts as a link.
Can you help me to learn more?
(Other definitions for dropout that I've seen before include "Free spirit" , "Student who fails to complete a college course" , "Restart (rugby game)" , "A student no longer" , "Further education deserter" .)