Mali's flourishing religion (5)
I believe the answer is:
islam
'religion' is the definition.
(Islam is a religion)
'mali's flourishing' is the wordplay.
'flourishing' indicates an anagram (letters grow or flourish differently).
'malis' anagrammed gives 'ISLAM'.
(Other definitions for islam that I've seen before include "Adherents of a religion" , "Religion of the Koran" , "Major world religion" , "Faith with five pillars" , "Religion based on teachings of Muhammad" .)