Sentence:  Within the membership of this group , as has been found true of men in other professional or trade associations , the most ready portrayal of oneself to `` the public '' is that of a neutral agent simply <WSD>serving</WSD> the interests of a seller or buyer and mediating between them . 
Meaning of the word marked with <WSD> tags:  devote (part of) one's life or efforts to, as of countries, institutions, or ideas