Possible Clues:

• Four or six in rehearsal? That's not important
• Hearing about 6 like 1
• Minor, four, appearing in a court case
• Small getting six in Test
• Minor investigation about WW2 rocket
• Rival it, being unimportant
• Getting only four in a test is not worth talking about
• Small-time opponent hides one to be petty
• Piffling
• Quartet in criminal case that's petty