Bird finding many changes on top of hill (5)
I believe the answer is:
mynah
'bird' is the definition.
(mynah is a kind of bird)
'many changes on top of hill' is the wordplay.
'changes' indicates an anagram.
'on top of' indicates taking the first letters.
The first letter of 'hill' is 'h'.
'many' is an anagram of 'myna'.
'myna'+'h'='MYNAH'
'finding' is the link.
(Other definitions for mynah that I've seen before include "Talking bird" , "Asian starling mimicking human speech" .)