Criminal who would be quite happy to get bird (3,7)
I believe the answer is:
cat burglar
'criminal' is the definition.
(cat burglar is a kind of criminal)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for cat burglar that I've seen before include "Thief entering via an upper storey" , "Housebreaker entering by upper windows, skylights etc" , "having taking ways?" , "Criminal who can climb" , "What Macavity could be" .)