The most common and most likely answer to this crossword clue is the 6 letter word BURROW
B
U
R
R
O
W
More clues leading to the result BURROW
- Dispute below Polish northbound tunnel
- Set menu item in Mexico with / without wine
- Top of hill outside ancient city provides hidden shelter
- 14 is donkey to hit wicket
- Place of refuge for in second line around old city
- Rub the wrong way, quarrel and retreat
- Donkey starts to whimper in den
- Pack animal with place of refuge
Buddy explains!

The straight part
We know that "retreat" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case retreat = burrow.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 BURROW mean?
BURROW noun- A mountain.
- A hill.
- A mound of earth and stones raised over a grave or graves.
- A heap of rubbish, attle, or other such refuse.
- A small vehicle used to carry a load and pulled or pushed by hand.
- (saltworks) A wicker case in which salt is put to drain.
- A castrated boar.
- A long sleeveless flannel garment for infants.
- A fortified town.
- A town or city.
- A town having a municipal corporation and certain traditional rights.
- An administrative district in some cities, e.g., London.
- An administrative unit of a city which, under most circumstances according to state or national law, would be considered a larger or more powerful entity; most commonly used in American English to define the five counties that make up New York City.
- Other similar administrative units in cities and states in various parts of the world.
- A district in Alaska having powers similar to a county.
- An association of men who gave pledges or sureties to the king for the good behaviour of each other.
- The pledge or surety thus given.
- A tunnel or hole, often as dug by a small creature.
- A heap or heaps of rubbish or refuse.
- To dig a tunnel or hole
- (with adverbial of direction) to move underneath or press up against in search of safety or comfort
- (with into) to investigate thoroughly