The term 'Mark with an Iron' refers to the process of branding, which is a method of marking livestock or other animals with a hot iron. The crossword solutions for this term are BRAND (5 letters) and SCORCH (6 letters). Branding is a traditional practice that has been used for centuries to identify animals and their owners. The process involves heating an iron until it is very hot and then pressing it onto the animal's skin, leaving a permanent mark. The heat from the iron causes the skin to SCORCH, hence the solution SCORCH.