Possible Clues:

• Grand Ole Opry genre, briefly, that's also a hint to 21-, 33-, 41- and 51-Across
• Nashville music, for short
• Grand Ole Opry genre, briefly
• Nashville sound, for short
• Grand Ole Opry offering, for short
• Reba's genre, briefly
• Music category
• Nashville music
• Oft-twangy genre, briefly
• Music genre, briefly