Sentence:  He had assumed that all these buildings had been divided into apartments , but this one , from a glance at the hall furnishings , was obviously still a <WSD>functioning</WSD> town house , and its owners were in residence ; that made it doubtful as the hiding place of a man whose plans had to be made in advance . 
Meaning of the word marked with <WSD> tags:  performing or able to perform its regular function