你的句子用 one-hour 也可以，但意思稍有区别。

比较而言，one-hour 只表示时间长度，意思是“一个小时的”，类似的表达有two-hour, three-hour, four-hour, two-day, three-week, four month, five-year 等。如：

The day was split up into 6 one-hour classes. 一天分作6节课, 每节课一小时。

There is often a one-hour wait to see a doctor. 找医生看病常常得等1 个小时。

After a one-hour workout, Sam felt good. 经过一个小时的练习，萨姆感觉不错。

It was very difficult to encapsulate the story of the revolution in a single one-hour documentary. 将革命的前后经过浓缩成一部一小时的纪录片是很难的。

而 hour-long 强调持续性，意思是“持续一小时的”（=lasting an hour），类似的表达有day-long, week-long, month-long, year-long等。如：

The new hour-long program is anchored by Mark McEwen. 这个1小时长的新节目由马克•麦克尤恩主持。

Student tour guides take visitors on a one-hour tour of the campus. 学生导游带参观者在校园里进行一个小时的游览。