‘Clerks III’ is Kevin Smith’s sentimental ode to the movie that launched his career

Grappling with middle age, “Clerks III” turns out to be unexpectedly sentimental and nostalgic, reflecting that writer-director-editor-co-star Kevin Smith inherently recognizes this will likely be the gang’s final visit to Quick Stop Groceries. If so, it’s an uneven if gentle way to hang out the “We’re closed” sign.