Warmer Cockney animal (5)
I believe the answer is:
otter
This clue is a double definition.
'warmer cockney' is the first definition.
('hotter' - 'hot' can be a synonym of 'warm' - said with a cockney accent, dropping the 'H')
'animal' is the second definition.
(I've seen this before)
(Other definitions for otter that I've seen before include "Semi-aquatic mammal" , "Aquatic member of weasel family" , "Semi-aquatic creature" , "Freshwater mammal with dark brown fur" , "Fish-eating water animal with brown fur and flat tail" .)