Presumably it is the section that is ambient, but what does this mean? It once meant revolving, but now means surrounding, as in the ambient air. Is the grocery, then, spread about the store? In which case it is neither a section nor small.
The OED notes that as an epithet of the air, "it is often ignorantly put for `limpid', or otherwise misused", and one suspects that The Grocer mistook the `bien' part of the word for the French. So perhaps it is the grocery that is ambient after all.