One animal of some wandering round in it (5)
I believe the answer is:
moose
'one animal' is the definition.
(type of animal)
'some wandering round in it' is the wordplay.
'wandering' is an anagram indicator.
'round' becomes 'o' (round can mean a round object).
'in it' indicates putting letters inside.
'some' with letters rearranged gives 'mose'.
'mose' going around 'o' is 'MOOSE'.
'of' is the link.
(Other definitions for moose that I've seen before include "beasts" , "Animal" , "Large northern deer" , "US deer with enormous antlers" , "North American deer" .)