I'd argue that there's no such thing at all as the clock resetting. I can't recall if this is something that used to be in the rule or just something that's always been assumed to be allowed, but the current text of the rule doesn't support it.
A maximum of 30 seconds is allowed to each player to make a throw after 1) the previous player has thrown; and, 2) the player has had a reasonable amount of time to arrive at the disc; and, 3) the playing area is clear and free of distractions.
I read that as once the clock starts, that's it. Once the player is at his lie and there are no distractions, the clock starts and there's no stopping it until the throw is made. If another distraction comes up, it's up to the player to either ignore it or try to wait it out based on whether or not he can stay within his 30 seconds. Maybe I'm just missing it, but show me where the book says the 30 seconds can be restarted.