Try very large European bird (5)
I believe the answer is:
goose
'bird' is the definition.
(I know that goose is a type of domesticated bird)
'try very large european' is the wordplay.
'try' becomes 'go' (both can mean an attempt).
'very large' becomes 'os' (abbreviation for oversize).
'european' becomes 'E' (abbreviation e.g. EU).
'go'+'os'+'e'='GOOSE'
(Other definitions for goose that I've seen before include "Marches in an odd fashion" , "Supposedly foolish bird" , "Christmas bird?" , "Large waterbird" , "Gander's mate" .)