XML : How to retrieve specific Event using specific condition in xpath?

  <List>     <Event>        <eventTime>2016-08-03T15:41:12.000+05:30</eventTime>        <e:PlaceHolder xmlns:e="http://dpmt.element.com">US</e:PlaceHolder>        <e:flag xmlns:e="http://dpmt.rmg.org/pq/rs">true</e:flag>        <e:flag1 xmlns:e="http://dpmt.rmg.org/pq/rs">false</e:flag1>     </Event>     <Event>        <eventTime>2016-08-01T19:41:12.000+05:30</eventTime>     </Event>  </List>    

I have stored my XML document in such a way , which may contains multiple tags, using the X-Path query , I want to fetch only that event , that have e:flag value true, In my case i have to get only first event tag using where clause. I need a generic query using EXTRACT or ExtractValue function by condition in where clause to check it's flag value.

I am writing query in this way :-

SELECT * FROM (SELECT EXTRACT(doc,'//List').getClobVal() AS doc FROM my_table) T;

Thanks in advance,