Python or boa (5)
I believe the answer is:
snake
I believe this clue is a double definition.
'python' is the first definition.
(thesaurus)
'boa' is the second definition.
(I've seen this in another clue)
(Other definitions for snake that I've seen before include "For instance, adder" , "former EC currency band" , "Slithering reptile" , "Serpent" , "Limbless reptile" .)