Sort of fur that's sexier topless (5)
I believe the answer is:
otter
'sort of fur' is the definition.
'sexier topless' is the wordplay.
'sexier' becomes 'hotter' ('hot' can be similar in meaning to 'sexy').
'topless' means to remove the first letter.
'hotter' with its initial letter removed is 'OTTER'.
'that's' acts as a link.
(Other definitions for otter that I've seen before include "Lithe swimmer" , "River animal" , "Carnivorous aquatic mammal" , "Fish-eater of the weasel family" , "Fish-eating mammal" .)