The term 'OPENING PIECE' can be solved by two crossword solutions: 'PRELUDE' (7 letters) and 'KNOB' (4 letters). A PRELUDE is a short piece of music that is played before a larger piece or performance. It is often used to introduce the main theme of the piece. A KNOB is a round handle or dial used to control the settings on a machine or device. Knobs are commonly used to adjust the volume, temperature, or other settings on a variety of machines.