The most common and most likely answer to this crossword clue is the 9 letter word GOLDCREST
I've seen this crossword clue in The Guardian
G
O
L
D
C
R
E
S
T
More clues leading to the result GOLDCREST
- Winger or prop overlooked by clubs
- Grand heraldic device incorporating grey bird?
- Bird seen in grand, ancient coat of arms
- It flies German historic family insignia
- Bird in medal atop heraldic device
- Winger heading for goal, getting on top
- Clubs on break after midnight with early bird
- Grand ancient heraldic device, a bird
- Bird beginning to go by grey ridge
- ‘Grand’ and ‘most ancient’ describe wings of Christopher Wren?
Buddy explains!

The straight part
We know that "Wren" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wren = goldcrest.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 GOLDCREST mean?
GOLDCREST noun- A very small passerine bird, Regulus regulus, that breeds in Eurasia.