Merrimac Square sits at the middle of an old carriage-building town, and the streets running off it are lined with front lawns barely deeper than a porch — the kind of yards where every wobble in a line shows. Clean Cut Lawn Care does its best work in that tight geometry: mowing in straight passes, trimming tight to granite steps and hydrants, then cutting an edge along the sidewalk so clean it looks drawn. Midday in July the mowers run hot and the air smells like cut grass for a block in either direction, which is about the most agreeable thing a summer street can smell like. Seasonal cleanups handle the shoulder months, when the maples on these blocks drop more than any small yard can hold. The name is the whole promise, and the finished edge is where it gets kept.