Thanks for the reply, Dillen, although it's a bit belated...

After doing some more research, I tend to believe that Program clearance executive is a person who obtains an agreement from a TV company/station to air the show that is being produced. In TV producers' lingo, "to clear a program (or show)" means just that.

Clearance associate, on the other hand, is (most likely) a person who handles things like obtaining permissions to use copyrighted works and such.