Change Of Clothes
Spare Clothes
noun, verbal noun
You know how 替える is "to replace"? Well, you're replacing what you wear. That's a change of clothes, or spare clothes.
The reading is 着る and 替える put together. The か goes to が.
母は、私の着替えを持ってくるのを忘れた事を謝りました。
My mother apologized for forgetting to bring me a change of clothes.