Treacherous person (5)
'treacherous person' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for snake that I've seen before include "Long slender reptile" , "Slithering reptile" , "Asp, perhaps?" , "Carnivorous reptile" , "For instance, adder" .)
(Other definitions for barracuda that I've seen before include "Voracious tropical fish" , "Large predatory sea fish" , "fearsome swimmer" , "Marine attacker" , "Voracious marine fish" .)