Asian state prison turning over an informer (7)
I believe the answer is:
gujarat
'asian state' is the definition.
(Gujarat is an Indian state)
'prison turning over an informer' is the wordplay.
'prison' becomes 'jug' (slang term).
'turning over' says the letters should be written in reverse.
'an' becomes 'a'.
'informer' becomes 'rat' (synonyms).
'jug' reversed gives 'guj'.
'guj'+'a'+'rat'='GUJARAT'
(Other definitions for gujarat that I've seen before include "Part of India" , "state in India" .)