A mass rising in Indian state (5)
I believe the answer is:
assam
'indian state' is the definition.
(I've seen this before)
'a mass rising' is the wordplay.
'rising' says the letters should be written in reverse (going up in a down clue).
'mass' back-to-front is 'ssam'.
'a'+'ssam'='ASSAM'
'in' acts as a link.
(Other definitions for assam that I've seen before include "Leaves to get in hot water" , "Indian state known for its tea production" , "Type of tea" , "Indian state known for tea growing" , "Tea-growing region" .)