Creature in a new feature climbing tops of Kensington East (3,5)

'creature' is the definition.
(type of animal)

'a new feature climbing tops of kensington east' is the wordplay.
'a' becomes 'an'.
'new feature' becomes 'star' (starring is a kind of featuring. I am not sure about the 'new' bit.).
'climbing' shows that the letters should be reversed in order (in a down clue, letters climb up).
'tops of' says to take the initial letters.
The first letters of 'kensington east' is 'ke'.
'an'+'star'='anstar'
'anstar' backwards is 'ratsna'.
'ratsna'+'ke'='RAT SNAKE'

'in' is the link.