Rule Definition
As a rule of thumb, every table in every database should have a clustered index. Most of the time the clustered index should be on a column that monotonically increases--such as an identity column, or some other column where the value is increasing--and is unique. In many cases, the primary key is the ideal column for a clustered index. This recommandation of using the PK for the clustered index is NOT true for MS SQL-Server 6,5 because of "hotspots" but is true for other versions.

Remediation
Change an existing index to a clustered one (probably the index associated to the PK). Note that you can only have one clustered index per table.

Violation Code Sample

create table MyTable ( C1 int identity, C2 varchar(250))

Fixed Code Sample

create table MyTable ( C1 int identity, C2 varchar(250))

create clustered index MyTable_PK on MyTable( C1)