Previous 'leap second' events have been and gone without any disruption for Clarity software versions.
Whilst a specific test hasn't been carried out in the various platforms in order to see how this might impact, there has been no precedent for concern over the previous occurrences (I believe the last one was ~3 years ago in 2012, and it posed no issues), and there are no problems anticipated to come from this one.
If anything, it is an event that is more likely to impact/confuse either the OS or the JVM update you are using than it would the Clarity application directly (which if they stop/error out, could still cause you to be unable to run your Clarity services), so I would suggest checking with your associated platform vendors for information, and considering whether or not your OS updates or JVM updates could do with an update (JVM updates can also help with other globalization change impacts, such as changes in timezones or currencies in the world).
For example, if you're using JDK 1.7.0 update 6, then this would be considered fairly old by todays standards, and you might want to go up to JDK 1.7.0 update 77 (or higher, but staying within the 1.7.0 range) in order to mitigate against such differences. Staying uptodate on OS patches is more likely to be taken care of already, given the various new vulnerabilities they help to block and a general insistence on IT departments to enforce their application, but I would still check and see what the position of the OS vendor is on this topic for your version.
CA PPM Tuesday Tip: Leap Second