The most common and most likely answer to this crossword clue is the 6 letter word PULLET
I've seen this crossword clue in The Guardian
P
U
L
L
E
T
More clues leading to the result PULLET
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 = pullet.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 PULLET mean?
PULLET noun- A young hen, especially one less than a year old.
- A spineless person; a coward.
- A young girl.