The answer to your question has to do with where you live. If you live in the U.S., every state has certain laws and regulations regarding licensing of psychologists. In California, for instance, you are not able to call yourself a psychologist till you get a license from the state, but once you get that license no one really cares whether you have a degree in clinical psychology and you can go ahead and do clinical work.
I think you should take a look at the board of psychology site (the link is below) and see the information regarding the place in which you live.
http://www.psychboard.ca.gov/
