A change involves one zoo feature (6)
I believe the answer is:
aviary
'zoo feature' is the definition.
(I've seen this in another clue)
'a change involves one' is the wordplay.
'change' becomes 'vary' (synonyms).
'involves' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'vary' going around 'i' is 'viary'.
'a'+'viary'='AVIARY'
(Other definitions for aviary that I've seen before include "Place where birds are kept" , "Where flights are limited" , "chat room?" , "Bird sanctuary" , "wildlife centre" .)