His law affected India's lingua franca (7)
I believe the answer is:
swahili
'lingua franca' is the definition.
(lingua franca in east Africa)
'his law affected india's' is the wordplay.
'affected' indicates an anagram.
'india' becomes 'i' (phonetic alphabet: alpha, bravo, charlie etc.).
'his'+'law'='hislaw'
'hislaw' anagrammed gives 'swahil'.
'swahil'+'i'='SWAHILI'
(Other definitions for swahili that I've seen before include "African people" , "Language giving us bwana, safari" , "Major Bantu language widely used in E Africa" , "Language of Kenya and lingua franca of other African areas" , "Language widespread in East Africa" .)