Goes mad about old bird (5)
I believe the answer is:
goose
'bird' is the definition.
(I know that goose is a type of domesticated bird)
'goes mad about old' is the wordplay.
'mad' is an anagram indicator.
'about' indicates putting letters inside.
'old' becomes 'o' (abbreviation).
'goes' is an anagram of 'gose'.
'gose' going around 'o' is 'GOOSE'.
(Other definitions for goose that I've seen before include "Migratory aquatic bird" , "Gander" , "alternative to 7 [TURKEY]" , "Christmas bird?" , "Large water bird" .)