Usually, Basho's famous haiku, when written with a translation, is presented thus:
古池や
蛙飛び込む
水の音
And translated roughly (similar to three out of five translations available in Wikisource):
An old pond
A frog leaps
The sound of water
However, there are inversions of order of the last two lines, as was brought to my attention in a recent post I made in the Literature Stack Exchange:
An old pond
The sound of water
As a frog leaps in/Of a frog leaping in
Here, the second line is modified by the third, whereas in the first, they stand separate.
In Japanese, what type of clause is the phrase 「蛙飛び込む」 in this haiku?