Bird that's not content with banana custard (7)
I believe the answer is:
bustard
'bird' is the definition.
(bustard is a kind of bird)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for bustard that I've seen before include "Large heavy bird" , "flyer" , "See large bird" , "Bad rust (anag.)" , "Long-legged, heavy-bodied bird" .)