I doubt this is a species under the genus Clausena of the family Rutaceae

So the fruit edible?  Any photos of the flowers close-up?

You may contact Dr. K. Narayanan Nair

for identification

It may be Clausena heptaphylla (Roxb.) Wight & Arn.,which is reported from flora of Assam; its name is Kebu -taye(Abor), Dieng -siang-mat(Khasi)The leaves chewed with pawn, used flavouring tobacco.

Thank you all for your valuable answer. The leaves of this species ranges between 4-5 in. long which is smaller than the Clausena heptaphylla which is 9-15 in. long as per Flora of Assam. For the species C. heptaphylla fruiting occurs in cold season, but for this unknown species fruiting recorded in the month of May. So still there is a confusion to accept this species as C. heptaphylla.

Dr. K. Narayanan Nair who has revised the Indian members of the Rutaceae has identified the plant to be of Clausena heptaphylla (Roxb.) Wight & Arn. ex Steudel .

Gitamani--you may have encountered an ecotype of the species, which is confusing taxonomically because the original species description of any plant, is from a single ecotype of that species to begin with.  

For example, when I did my ecotype research on one native grass growing in the wild within a 150 miles radius, I found a dozen very distinctive ecotypes that I grew in a common garden experiment, and when compared to the original species description, you would have classified all of the ecotypes as different species.  You can see pictures at http://www.ecoseeds.com/common.html.  

Clausena heptaphylla (Roxb.) Wight & Arn. ex Steudel . Family Rutaceae Rare species available Assam region

Gitamani Dutta

This plant seems to be Clausena excavata Burm.f.

https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:772128-1

Thanks!