Average American falls down in a quarter of North African cities (6)
I believe the answer is:
medina
'quarter of north african cities' is the definition.
'medina' can be an answer for 'quarter' (I have seen 'old quarter' mean 'medina' so perhaps 'quarter' could also mean 'medina'). I'm not certain of the 'of north african cities' bit.
'average american falls down in a' is the wordplay.
'average american falls down' becomes 'med' (I can't justify this - if you can you should believe this answer much more).
'med'+'in'+'a'='MEDINA'
Can you help me to learn more?
(Other definitions for medina that I've seen before include "Native quarter in North African cities" , "Second most holy city of Islam, in Saudi Arabia" , "Holy city in Saudi Arabia for maiden" , "Location of the tomb of Mohammed" , "Mohammed burial city" .)