The most common and most likely answer to this crossword clue is the 6 letter word SHRINK
I've seen this crossword clue in The Guardian
S
H
R
I
N
K
More clues leading to the result SHRINK
- Holding hearts, go down in contract
- So-called trick cyclist to stop shooting film
- Film psychiatrist with bad reputation in the US
- Therapist’s contract
- Hang back in silence where area is covered in ice
- Quail bone adorning one king and another
- Psychiatrist‘s contract
- Psychiatrist‘s contract?
- Person who analyses contract
- Reduce personnel during depression
Buddy explains!

The straight part
We know that "Quail" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case quail = shrink.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 SHRINK mean?
SHRINK noun- Shrinkage; contraction; recoil.
- (sometimes derogatory) A psychiatrist or psychotherapist.
- Loss of inventory, for example due to shoplifting or not selling items before their expiration date.
- To cause to become smaller.
- To become smaller; to contract.
- To cower or flinch.
- To draw back; to withdraw.
- To withdraw or retire, as from danger.
- To move back or away, especially because of fear or disgust.