Rain fall on sash in African capital (7)
I believe the answer is:
nairobi
'african capital' is the definition.
(capital of Kenya)
'rain fall on sash' is the wordplay.
'fall' indicates anagramming the letters (I've seen 'fallen' mean this).
'on' says to put letters next to each other.
'sash' becomes 'obi' (type of Japanese sash or belt).
'rain' anagrammed gives 'nair'.
'nair'+'obi'='NAIROBI'
'in' is the link.
(Other definitions for nairobi that I've seen before include "Kenyan capital" , "Foreign capital" , "East African capital" , "African city" , "Kenya's capital city" .)