I don't understand all of this fuss over the definition of time.
We measure time. We measure it with great precision. The ways that we use to measure time define it very well. Anybody who knows how to measure time, knows what time is.
The arguments as to whether time is part of the fundamental structure of the universe - those are just foolish word games. We understand the meaning of "time" far better than we understand the meaning of "fundamental" or "structure" or "universe".