The most common and most likely answer to this crossword clue is the 9 letter word REDBREAST
I've seen this crossword clue in Financial Times
R
E
D
B
R
E
A
S
T
More clues leading to the result REDBREAST
- Darts, beer, excited Robin?
- Bird — star breed in trouble
- Bird having resources — tail first — to break perch
- Support saving breadcrumbs for bird
- Robin left-wing as Bert’s revolutionary?
- Flapper in recumbent convalescence, Spooner said
- Robin runs into ruddy animal
- Confused rat breeds with bird!
- Robin arrested, stupidly pinching book
- Winger starred with flankers in blue pants
Buddy explains!

The straight part
We know that "Flapper" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case flapper = redbreast.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 REDBREAST mean?
REDBREAST noun- Any of several unrelated birds that have a red breast