The most common and most likely answer to this crossword clue is the 7 letter word ROOSTED
I've seen this crossword clue in Financial Times
R
O
O
S
T
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D
More clues leading to the result ROOSTED
Buddy explains!

The straight part
We know that "Perched as bird" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case perched as bird = roosted.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 ROOSTED mean?
ROOSTED verb- (of birds or bats) To settle on a perch in order to sleep or rest
- To spend the night
- To rout out of bed; to rouse
- To harass, to treat in a rough way.
- To arrest
- To drive strongly