Farmyard animal -- one's scattered birds (7)
I believe the answer is:
pigeons
'birds' is the definition.
(pigeon is a kind of bird)
'farmyard animal one's scattered' is the wordplay.
'farmyard animal' becomes 'pig' (I've seen this before).
'scattered' indicates an anagram.
'ones' with letters rearranged gives 'eons'.
'pig'+'eons'='PIGEONS'
(Other definitions for pigeons that I've seen before include "Spin ego around the birds" , "traditional pie filling" , "Columbiform birds" , "Cooing birds" , "Town birds" .)