Dave Bonta's "Stand-in" is only a few words long, but it opens up a strange, quiet scene. The speaker is away from home, and in their absence a clock keeps going. They can't actually hear it, yet they imagine it ticking in the empty room, doing its job with nobody there to listen.
The title matters here. The clock is a stand-in: it takes the speaker's place, keeping watch over the house the way a person would. That idea leads to the odd, tender last line, "I owe it a letter." We usually write letters to people, so the speaker is treating the clock almost like a friend left behind, someone who deserves news or thanks.
The mood is wistful and a little playful. There is loneliness in the picture of an unattended room, but also affection. The poem suggests how objects can feel like companions, and how time carries on whether or not we are present.