Sentence:  It is significant that the Catskills , which used to be the summer playground for older teen-agers , a kind of summer suburb of New York , no longer attracts them in great numbers - except for those who work there as waiters , bus boys , or <WSD>counselors</WSD> in the day camps . 
Meaning of the word marked with <WSD> tags:  someone who has supervisory duties at a summer camp