Letter from India, one put in language from the east (7)
I believe the answer is:
initial
'letter' is the definition.
(I know that initial is a type of letter)
'india one put in language from the east' is the wordplay.
'india' becomes 'i' (phonetic alphabet: alpha, bravo, charlie etc.).
'one' becomes 'i' (Roman numeral).
'put in' is an insertion indicator.
'language' becomes 'latin' (Latin is an example).
'from the east' says the letters should be written backwards (on a map from right to left).
'i' going into 'latin' is 'laitin'.
'laitin' written backwards gives 'nitial'.
'i'+'nitial'='INITIAL'
'from' acts as a link.
(Other definitions for initial that I've seen before include "Occurring at the start" , "First letter (of a word)" , "Word's first letter" , "Sign" , "Approve" .)