SQL Db Create Tables And Cluster Primary Key

With the last table being created below, it has a clustered primary key.One of the fields it is referencing on the previous table, courseId, can NOT be unique.But without it being unique, the cluster primary key won't work.Is there another way to achieve what I am trying to do here?CREATE TABLE dbo.courseScores   (          courseId varchar(20) NOT NULL     CONSTRAINT FK_courseId_courseStructure2 FOREIGN KEY (courseId)    REFERENCES courseStructure (courseId), 

          studentId varchar(20) NOT NULL    CONSTRAINT FK_studentId_students2 FOREIGN KEY (studentId)    REFERENCES students (studentId), 

     CONSTRAINT PK_courseScore PRIMARY KEY CLUSTERED (courseId, studentId)

          )

 

CREATE TABLE dbo.objScores  (             objID varchar(20) NOT NULL    CONSTRAINT FK_objId_objstructure FOREIGN KEY (objID)    REFERENCES objStructure (objID), 

    studentId varchar(20) NOT NULL    CONSTRAINT FK_studentId_students3 FOREIGN KEY (studentId)    REFERENCES students (studentId), 

    courseId varchar(20) NOT NULL    CONSTRAINT FK_course FOREIGN KEY (courseId)    REFERENCES courseScores  (courseId),                     CONSTRAINT PK_objScores PRIMARY KEY CLUSTERED (objID, studentId, courseId)           )

Thanks all,Zath