Solitary individual city dweller dismissing academic (5)
I believe the answer is:
loner
'solitary individual' is the definition.
(I've seen this before)
'city dweller dismissing academic' is the wordplay.
'city dweller' becomes 'londoner' (I've seen this before).
'dismissing' indicates named letters should be taken away.
'academic' becomes 'don' (I've seen this before).
'londoner' with 'don' taken out is 'LONER'.
(Other definitions for loner that I've seen before include "person, one hating company" , "Introvert" , "Person who prefers his own company" , "One who avoids company" , "Individualist" .)