1917 cover from Russia, which town?

[Graham Mark]

In chewing the cud with a colleague this afternoon I mentioned this recent acquisition saying I could not trace the town of origin,  RENGU is clear but the remainder of the word is less well inked and over the stamp.  Can anyone tell me the town name please?  I cannot find a Russian town beginning as this one in either a world gazetteer or a world atlas.
The interest for me is that this cover from Russia 8 Aug 17, to Switzerland 23 Nov 17, was routed via London where it was censored by the French team which had been working in London since the Spring of 1916.  The reader of the contents was "number 27" and the desk was 912.  The arrangement with the British was designed to speed the flow of work in the censorships.
The letter was forwarded from Lausanne to Saanen where it was back-stamped the next day.
Best regards to all
Graham

[Howard Weinert]

The town on the cancel is Rengu in Liflyand province (i.e., Estonia). It is near Yuryev (now called Tartu).

[Graham Mark]

Thank you Howard
With best regards
Graham