The answer to the crossword question that states “an arm and a leg” is LIMBS. This phrase is commonly used to describe something that is very expensive or costly. The phrase “an arm and a leg” is believed to have originated from the idea that losing a limb would be a tremendous sacrifice, and something that one would only do in exchange for a high cost. Therefore, the phrase has become synonymous with the idea of sacrificing a great deal for something, either financially or otherwise. In this context, the answer to the crossword question is simply “limbs,” which refers to the arms and legs that make up our bodies and are often used in this expression.