Animal right behind snake (4)
I believe the answer is:
boar
'animal' is the definition.
(I've seen this before)
'right behind snake' is the wordplay.
'right' becomes 'r' (common abbreviation).
'behind' says to put letters next to each other.
'snake' becomes 'boa' (boa is a kind of snake).
'r' after 'boa' is 'BOAR'.
(Other definitions for boar that I've seen before include "Uncastrated male hog" , "A wild male pig" , "Wild swine" , "The head for drink Falstaff had" , "Resting place for birds or bats" .)