Solution to Ring Cycle by Hedge-sparrow

 Solution to Ring Cycle by Hedge-sparrow

The theme is the set of seven O ANTIPHONS (also known as the Great Os of Advent), which are Magnificat antiphons used at vespers on the final seven days of Advent.  The title of each antiphon comprises the word O followed by a Biblical name of Christ.  Six of the Biblical names – SAPIENTIA, ADONAI, RADIX JESSE, CLAVIS DAVID, ORIENS AND REX GENTIUM, appear as unclued entries in the grid.  The seventh, EMMANUEL, occurs hidden in the final grid in the shape of an O (to be indicated by solvers).