I posted the following answer to this on another thread (and community - visibility may be limited to the original so I will quote myself in full): https://communities.ca.com/message/241803882#241803882
There isn't an official answer as yet - it will come, but at the moment it depends also on a change of the JDBC driver versions we use and adequate testing, along with any other material differences between the DBMS versions that need supporting. It may come as early as the next release, and for anybody enquiring they should probably be directed to and follow updates to this customer-facing community thread where product management have already supplied some answers:
Road map of Oracle 12c support
Note that it is almost guaranteed that only a new release of Clarity will offer this support, and that backporting it to existing releases just doesn't happen (a patch would require too much testing effort).
There isn't another answer to give at this time, please note the part in bold. I would suggest following the quoted thread link (Road map of Oracle 12c support) for any further updates that may be made.