Sentence:  He added in conclusion that he strongly disliked the police coming and sticking its nose into his affairs and, since the horror which such actions inspired in him was not far from making him wish to vomit, he extracted from his pocket a silken square of the colour of the lilac flower (the one that isn't white) but impregnated with Barbouze, the Fior perfume, and with it dabbed his <WSD>snitch</WSD>. 
Meaning of the word marked with <WSD> tags:  A nose.