Crossword Puzzle Division rivals of the Rays

Clue: Division rivals of the Rays

Theater division (AISLE with 5 letters)
Division with Jays and Rays (ALEAST with 6 letters)
Plane seating division (and the key to this puzzle's theme) (CLASS with 5 letters)
Office division: Abbr. (DEPT with 4 letters)
Rays' rivals (REDSOX with 6 letters)
Investigative division (and puzzle theme hint) (INTERNALAFFAIRS with 15 letters)
Office of matins division (NOCTURN with 7 letters)
Theater offering (e.g. DRAMA with 5 letters)
Theater offering, sometimes (DRAMA with 5 letters)
Theater offerings (e.g. DRAMAS with 6 letters)