Related Clues:

• Essential as in pen that's disposable
• Like the math problem 1 + 1
• Fundamental part of fabric is absent, on reflection
• Fundamental, as a skill
• Essential bit of kebab as I chew
• Key is in vehicle, turning 180 degrees
• Degree thus simple?
• Reduced to the essentials
• No-frills degree, yes just like this
• Simple when written in pen
• Key turned in panic is abandoned
• Aggressively mainstream, in slang
• Like lye
• Selection of swing-music is abruptly rejected as standard
• First degree thus fundamental