Animal is a shy bear, by the sound of it (5)
I believe the answer is:
coypu
'animal' is the definition.
(I've seen this before)
'shy bear by the sound of it' is the wordplay.
'shy' becomes 'coy' (I've seen this before).
'bear' becomes 'poo'.
'by the sound of it' indicates a 'sounds like' (homophone) clue.
'coy'+'poo'='coypoo'
'coypoo' is a homophone of 'COYPU'.
'is a' is the link.
(Other definitions for coypu that I've seen before include "Large semiaquatic rodent" , "aquatic mammal" , "Aquatic beaver-like rodent" , "Large South American aquatic rodent" , "Animal -- source of nutria fur" .)