The most common and most likely answer to this crossword clue is the 7 letter word WAGTAIL
I've seen this crossword clue in The Times
W
A
G
T
A
I
L
More clues leading to the result WAGTAIL
- What dog may do to welcome garden visitor?
- Carry on endlessly with dog to get bird
- Other half of footballer’s story recounted in flyer
- Lament about a great bird
- Bird narrating story of Footballers’ Wives?
- What a gundog might do fetching bird?
- Bird dog’s happy to do this?
- German dog chases away wingless bird
- Bird with a good brush
- Bird dog will do it when happy
Buddy explains!

The straight part
We know that "bird" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bird = wagtail.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.
Crossword Answer definitions
WAGTAIL noun- Any of various small passerine birds of the family Motacillidae, of the Old World, notable for their long tails.