The term 'SANDAL'S LACK' is a reference to the LACK of toes that sandals have. The crossword solutions for this term are 'TOE' (3 letters) and 'TOES' (4 letters). Sandals are an open-toed type of footwear that typically consists of a sole held to the foot by straps. They are often worn in warm weather and are considered to be more casual than closed-TOE shoes. As such, they do not cover the toes, which is why they are referred to as having a 'LACK' of toes.