Solitary person left flipping US city (5)
I believe the answer is:
loner
'solitary person' is the definition.
(lonely person)
'left flipping us city' is the wordplay.
'left' becomes 'l' (common abbreviation).
'flipping' shows that the letters should be reversed in order.
'us city' becomes 'Reno' (city in Nevada).
'reno' back-to-front is 'oner'.
'l'+'oner'='LONER'
(Other definitions for loner that I've seen before include "Unaccompanied chap" , "Introvert" , "Solitary person" , "One liking solitude" , "person, one hating company" .)