A career gap on paper is rarely as alarming to a reader as it feels to the person who lived through it — but a paragraph of justification tends to draw more attention to it, not less.
One honest, brief line usually covers it: "Took twelve months for family caregiving" or "Freelanced while relocating" gives a reader enough context without inviting further scrutiny.
If something useful happened during the gap — a course, volunteer work, a personal project with real output — it's worth a short bullet of its own, treated like any other experience, not folded into an apology.
Save the fuller story for the interview, where tone and context can do work a resume line can't. The resume's job is just to not raise a flag that stops you from getting there.