The animal, making a row, started growling inside (5)
I believe the answer is:
tiger
'the animal' is the definition.
(tiger is a type of animal)
'a row started growling inside' is the wordplay.
'a row' becomes 'tier' (a tier is a row of things).
'started' suggests taking the first letters.
'inside' is an insertion indicator.
The first letter of 'growling' is 'g'.
'tier' going around 'g' is 'TIGER'.
'making' is the link.
(Other definitions for tiger that I've seen before include "Carnivorous large cat" , "Formidable competitor" , "Predator" , "Dynamo" , "Endangered carnivore" .)