Bird beginning to emit kitten-like sound we can hear (3)
I believe the answer is:
emu
'bird' is the definition.
(emu is a type of bird)
'beginning to emit kitten-like sound we can hear' is the wordplay.
'beginning to' indicates taking the first letters.
'kitten-like sound' becomes 'mew' (kittens mew).
'we can hear' indicates a 'sounds like' (homophone) clue.
The first letter of 'emit' is 'e'.
'mew' is a homophone of 'mu'.
'e'+'mu'='EMU'
(Other definitions for emu that I've seen before include "Long-necked bird" , "unit of measurement" , "Large Australian flightless bird" , "Physics unit" , "Hull's character" .)