The most common and most likely answer to this crossword clue is the 6 letter word GULLET
I've seen this crossword clue in The Daily Telegraph
G
U
L
L
E
T
Buddy explains!

The straight part
We know that "A little bird, you might surmise/passage getting food" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a little bird, you might surmise/passage getting food = gullet.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does GULLET mean?
GULLET noun- The throat or esophagus.
- The cytopharynx of a ciliate, through which food is ingested.
- The space between the teeth of a saw blade.
- A channel for water.
- A preparatory cut or channel in excavations, of sufficient width for the passage of earth wagons.
- The wide room under the pommel of a saddle, the hollow over the withers.