Animal to return to territory (5)
I believe the answer is:
otter
'animal' is the definition.
(I know that otter is a type of animal)
'return to territory' is the wordplay.
'return' shows that the letters should be reversed in order.
'territory' becomes 'ter' (I've seen this in other clues).
'to' reversed gives 'ot'.
'ot'+'ter'='OTTER'
'to' is the link.
(Other definitions for otter that I've seen before include "Holt dweller" , "Riverine mammal" , "River-dwelling mammal" , "carnivore is concerned" , "Mammal, 'Tarka'" .)