How to use 空下来？
Hi,
This situation is I went to the badminton court to play badminton but none of all the courts was available so I told a women at the counter that I'll be back at 4pm and then she said " 4点。。。能空下来“ Sorry that I'm not sure about what she said before 能.

I'm quite understand the meaning but confused with how to use that 空下来

Question

How to use 空下来 ？ 
Hi, 
This situation is I went to the badminton court to play badminton but none of all the courts was available so I told a women at the counter that I'll be back at 4pm and then she said " 4点。。。能空下来“ Sorry that I'm not sure about what she said before 能.

I'm quite understand the meaning but confused with how to use that 空下来

Answer

我现在很忙，等我空下来回复你。i am busy now,i will reply you when i have free time.

Answer

Hi Tailand friend. She means she won't be free until 4 o'clock. 空下来=闲着=to have free time