Good girl with time for bird (6)
I believe the answer is:
gannet
'for bird' is the definition.
(gannet is a kind of bird)
'good girl with time' is the wordplay.
'good' becomes 'g' (abbreviation).
'girl' becomes 'anne' (girl's name).
'with' means one lot of letters go next to another.
'time' becomes 't' (abbreviation).
'g'+'anne'+'t'='GANNET'
(Other definitions for gannet that I've seen before include "A large diving sea-bird" , "Heavily built marine bird" , "flyer" , "Big eater" , "Act in accordance (with command)" .)