Large South American snake (3)
(Other definitions for boa that I've seen before include "... cold-blooded creature" , "Python" , "Non-venomous snake" , "strangler" , "feathers around the neck?" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">large south american snake</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for anaconda that I've seen before include "large reptile" , "A slippery customer" , "crawler" , "Large South American snake" , "Large water snake" .)