Tor Browser should offer an option to clear history in PBM
By default, TBB uses private browsing mode. Cookies and other state (e.g. cache) are retained until the browser is restarted. There is neither an option to view the cookies nor to clear the history.
If the browser is left running for a long time, a lot of history can be linked.
TBB should offer an option to clear history in private browsing mode and/or clear all history associated with an URL bar domain when it is closed.