Marching with the group is a term used to describe the act of walking in unison with a group of people. It is often seen in military parades, where soldiers march in formation, or in marching bands, where musicians move in time with each other. The crossword solution for this term is 'instep', which refers to the part of the foot that connects the toes and the heel. Instep is also used to describe the act of stepping in time with the group.