Hi,
simply use "float interpolate" that would get you some smoothing, ahving a float trying to catch up with another, adjust the time it would take to smooth out more or less.
Also, you might want to check "Vector3 low pass filter" action, and maybe apply the same system to a float, thyt could be what you are after. If you need a custom action to low pass filter just a float, tell me, and I'll do it.
Bye,
Jean