Animal with a way back (5)
I believe the answer is:
llama
'animal' is the definition.
(I know that llama is a type of artiodactyl)
'with a way back' is the wordplay.
'with' means one lot of letters go next to another.
'way' becomes 'mall' (mall is a kind of way).
'back' is a reversal indicator.
'a'+'mall' is 'amall'.
'amall' in reverse letter order is 'LLAMA'.
(Other definitions for llama that I've seen before include "South American beast of burden" , "Camel-like wool source" , "South-American cud-chewing animal" , "S American animal like a camel with soft hair" , "South American relative of the camel" .)