The most common and most likely answer to this crossword clue is the 6 letter word CRAVEN
I've seen this crossword clue in The Daily Telegraph
C
R
A
V
E
N
More clues leading to the result CRAVEN
- Yellow bird hiding under roof of cottage
- Mean-spirited Conservative party at end of election
- Cowardly bird at foot of cape
- Catholic in retreat — Paradise he denied, being fearful
- Caught bird that’s black and yellow
- Mean-spirited, caught bird
- We’re told seabird is yellow
- Yellow head of colourful bird
- Chicken caught bird
- Caught bird, chicken
Buddy explains!

The straight part
We know that "chicken" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case chicken = craven.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 CRAVEN mean?
CRAVEN noun- A coward.
- To make craven.
- Unwilling to fight; lacking even the rudiments of courage; extremely cowardly.