The term 'MAKE CALLOUS' can be solved by the crossword solutions SEAR and CASEHARDEN. SEAR is a cooking technique that involves quickly heating food at a high temperature to create a browned, caramelized surface. CASEHARDEN is a process of hardening the surface of a metal object by applying heat and pressure. In this context, MAKE CALLOUS could refer to the process of hardening the skin of one's hands or feet by exposing them to extreme temperatures or pressure.