Row about tail of young animal (5)
I believe the answer is:
tiger
'animal' is the definition.
(tiger is a type of animal)
'row about tail of young' is the wordplay.
'row' becomes 'tier' (a tier is a row of things).
'about' indicates putting letters inside.
'tail of' suggests the final letters.
The last letter of 'young' is 'g'.
'tier' going around 'g' is 'TIGER'.
(Other definitions for tiger that I've seen before include "Fierce person" , "Striped big-cat" , "One noted for stripes" , "Striped carnivore" , "Beast - type of 1 across" .)