Sentence:  There was one little prim old lady, of very smiling and good-humoured appearance, who came <WSD>sidling</WSD> up to me from the end of a long passage, [...] 
Meaning of the word marked with <WSD> tags:  "In the intransitive sense often followed by" '''(up)''': to (cause something to) advance in a coy, furtive, or unobtrusive manner.