Creature in opening close to bush (5)
I believe the answer is:
sloth
'creature' is the definition.
(sloth is a kind of creature)
'opening close to bush' is the wordplay.
'opening' becomes 'slot' (slot is a kind of opening).
'close to' indicates one should take the final letters (the close/ending of).
The final letter of 'bush' is 'h'.
'slot'+'h'='SLOTH'
'in' is the link.
(Other definitions for sloth that I've seen before include "Arboreal animal" , "Arboreal creature" , "Sinful" , "Torpor" , "Inertia" .)