The term 'PART OF A SOCK' can be broken down into three crossword solutions: HEEL (4 letters), TOE (3 letters), and ANKLE (5 letters). The HEEL is the back of the sock, which is usually thicker than the rest of the sock and provides cushioning for the foot. The TOE is the front of the sock, which is usually thinner than the HEEL and helps to keep the sock in place. The ANKLE is the top of the sock, which is usually ribbed or elasticized to help keep the sock up on the leg. All three parts of a sock are essential for providing comfort and protection for the feet.