"Secarik..."

I often read word "secarik" being followed with "kertas". "Secarik kertas". A piece of paper. But I read this:

I wonder what does it mean "secarik langit biru" in that sentence. Does it mean "a piece of blue sky"? Doesn't that sound a bit weird? Sky has pieces? Now I need to find out and make sure about its meaning on KBBI.

Here is what I found on http://kbbi.web.id/:

So from the definition on that link, I concluded that the use "secarik" in a sentence "secarik langit biru" is not a correct usage.

Hmm, I wonder if this blog has made me as a grammar nazi now...