Possible Clues:

• They're treated as people, legally: Abbr
• S.&P. 500 listings: Abbr
• Funny Bill, familiarly
• Trig function, in short
• Secant's reciprocal (Abbr.)
• Trig
• Where Hippocrates Society might turn up?
• Let us sound green for the firms, perhaps
• 1980s sitcom star, familiarly
• Island in Mediterranean often associated with sin