This question has come up before.
In 2005,
the rules were different, and all electronic "motor[s], solenoid[s], pump[s] or other actuator[s]" were prohibited, other than the ones in the KOP. (This type of clutch is either a solenoid or other actuator.)
In 2010, the rules were more similar to 2012. In that case, the
Q&A noted that if the clutch did not contain a prohibited actuator (and implicitly, did not violate any other rules), it would be allowable. In 2010, there was some unresolved discussion about whether the clutch contained a true solenoid, or merely some other type of electromagnetic actuator.
For 2012, [R48] provides a new complication, because it now says "The only motors and actuators permitted on 2012 FRC Robots include" instead of "Motors specifically permitted on 2010 FRC ROBOTS include". This means that a new restriction on actuators has been explicitly added for this year.
Therefore, if the clutch contains a solenoid, then that solenoid must meet the specifications from the rulebook for the clutch to be legal. If the clutch
does not contain an appropriate solenoid (or other thing from [R48]), it's a prohibited actuator. (Of course, the device must also meet all other rules, particularly the ones dealing with custom circuits and power regulating devices for actuators.)
I think the rule is clear in its meaning, but not so clear in its intent. Why ban a device that was previously allowed, even as you allow solenoids for the first time in over 10 years (and possibly ever)? You might therefore want to raise it in the Q&A not for clarification, but with the intention of prompting FIRST to change the rule.