The term 'make amends for sin' can be expressed by the crossword solution 'EXPIATE, ' which is a seven-letter word. EXPIATE means to make amends or reparation for a wrong or an offense, usually through an act of sacrifice or penance. It is derived from the Latin verb expiare, which means to atone for a crime or sin. In religious contexts, expiation is often used to refer to the act of making amends for sins through prayer, repentance, and other acts of devotion.