I believe that questions marked with time-zone should be re-tagged with time, and time-zone should then be made a synonym for time. Mentioning the phrase "time zone" in the title and/or body of the question is enough.
utc (and other tags about specific time zones that might exist) must be deleted.
clock is ambiguous on a forum about software and hardware, and in my opinion should be replaced with either time or cpu (when it's about the CPU clock rate, as in Slower cpu (pstate) = slower ram performance?).