Little bird entered, empty inside, and ate (9)
I believe the answer is:
swallowed
'little' is the definition.
The answer and definition are not the same part of speech. However, adjectives and past participle verbs can sometimes define each other.
'bird entered empty inside and ate' is the wordplay.
I cannot really understand how this works, but
'bird' could be 'swallow' (swallow is a kind of bird) and 'swallow' is found within the answer.
'empty' could be 'e' (abbreviation e.g. on guages) and 'e' is found within the answer.
A single letter 'd' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for swallowed that I've seen before include "Meekly accepted" , "Gulped" , "believed" , "Ingested" , "drunk maybe" .)