Bird, dog also heard? (8)
I believe the answer is:
cockatoo
'bird' is the definition.
(cockatoo is a kind of bird)
'dog also heard?' is the wordplay.
I cannot really understand how this works, but
'also' could be 'too' (synonyms) and 'too' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for cockatoo that I've seen before include "Australasian parrot" , "Crested bird" , "Australian parrot" , "Illegal Aussie look-out man" , "White parrot" .)