The term 'PART OF ATV' can be broken down into two crossword solutions: ALL (3 letters) and TERRAIN (7 letters). All-TERRAIN vehicles (ATVs) are motorized vehicles that are designed to travel on a variety of terrains, such as sand, mud, snow, rocks, and grass. The 'ALL' in the crossword solution refers to the fact that ATVs are designed to traverse all types of TERRAIN, while the 'TERRAIN' solution refers to the various surfaces that ATVs are designed to handle.