An hourly clock has been requested several times. Currently the only way to know the time exactly is by doing a Save.
For travel time, several maps are no time to enter but an hour to leave (ex: inner spider cave, Sacred Well, Ziva's/Lindra's house, Tower of Dread). A few others like the Swamps or Vixenatrix' lair take several hours each way to represent a longer/more difficult journey.
Some actions take longer than an hour. Most are straightforward, like doing something at the forge or helping Rosy with baking (both are always two hours). One or two are variable...grinding wheat into flour can take up to three hours depending on how much wheat you're grinding. (Planting or harvesting crops seems like it should take time, but it doesn't.
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)
A big variable is making potions from the recipe book. Each potion takes an hour, but you can keep making them even as long as the book is still open...all the time (and fatigue!) is applied when you close the book. Each potion using the Chalice is a separate one-hour action (there's a ritual or something).