South American snake (8)
I believe the answer is:
anaconda
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">south american snake</span>' is the definition.<br/ ><span class="explanation-format__explanation">(anacondas are native to South America)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for anaconda that I've seen before include "Large snake of tropical S America" , "S. Am. constrictor snake" , "Strangler" , "Water-boa" , "Boa constrictor" .)