The Collaborative International Dictionary
                    Decoy-duck
                    
                        
                
                                                                    Decoy-duck \De*coy"-duck`\, n.
   A duck used to lure wild ducks into a decoy; hence, a person
   employed to lure others into danger. 
--Beau. & Fl.
Wiktionary
                    decoy-duck
                    
                        
                
                                                                    n. 1 A duck used to lure wild ducks into a decoy. 2 (context by extension English) One employed to lure others into danger.
Usage examples of "decoy-duck".
In the same room were his pretended wife, Catina, two Sclavonic-looking assassins, and the decoy-duck.