Field type Entity Reference as select list but based on value I want field with entity reference showed as select but based on value from the another field in the same form [radio button field] 
for example the entity reference field will list these values

-entity 1 
-entity 2 
-entity 3 
-entity 4 

and the field radio button will hold countries like so:

-England 
-Germany 

notice that the entities reference (Content Type) has field called country, so when i check the 
value "England" i want the field entity to be filtered based on England for ex:
-entity 1 &amp; -entity 4
and same if i clicked Germany.

is that applicable in Drupal 7 even by Views module, or i have to do it custom !?
You can use Dynamic dependent fields module.

Project page says:


  Makes field value or options depend on other field values when editing
  entity.