We most often meet e... ana... in a subclause, that is, in the second part of a sentence.

For example:

Kei te whakorongo ahai ki te wahine e waiata ana.
I am listening to the woman who singing.
or:
I am listening to the singing woman.

Kei te mātakitaki ahau i ngā tamariki e tākaro ana.
I am watching the children who are playing.
or:
I am watching the playing children.