City in African country's less than half-built (6)
I believe the answer is:
malibu
'city' is the definition.
'african country's less than half-built' is the wordplay.
'african country' becomes 'mali' (Mali is an example).
'less than half-built' becomes 'bu' (40% of 'built').
'mali'+'bu'='MALIBU'
'in' is the link.
(Other definitions for malibu that I've seen before include "Californian beach" , "Site of the Getty Villa museum" , "Californian surfing town" , "California beach" , "City in California" .)