it started working now, for 2 reasons:
1. I added <type>java.util.List</type> for <attribute> element in tld for clist.
2. I added clist in session and passed it to the tag from sessionScope.
But my question remains that if i declare that list in scripting why should'nt it take from page scope. I explicitly have to add it in any of the scope.
Also
creates a List. Then why it is giving me an error :
Attempt to convert String "Red,Blue,Indigo,Yellow,Green" to type "java.util.List", but there is no PropertyEditor for that type