How to exclude Cross apply to make it conditional
S.ID IN(SELECT DISTINCT ServiceEntryID
                        FROM
                          ServiceEntryPart M
                          CROSS APPLY
                          dbo.SplitStrings_Moden(M.ServiceTypeIDs, N',') M2
                          JOIN dbo.SplitStrings_Moden(@ServiceTypes, N',') P ON M2.Item = P.Item
                          INNER JOIN Part ON M.PartID = Part.ID
                              WHERE
@ActivePart is null or @ActivePart = Part.Active))