The most common and most likely answer to this crossword clue is the 6 letter word CANNON
I've seen this crossword clue in The Times
C
A
N
N
O
N
More clues leading to the result CANNON
- Nearly is unable to name piece of artillery
- Gun rule read out
- Cleric entertaining nonconformist leader shot at table
- Shot from gun
- Big old gun member of the clergy picked up
- Gun swindle implicating Frank?
- Pointless snooker shot from John Higgins’s sixth frame of Open
- It’s rumoured minister could get fired
- Priest reportedly shot playing billiards
- Clergyman taking a point to heart may be fired
Buddy explains!

The straight part
We know that "Gun" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case gun = cannon.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 CANNON mean?
CANNON noun- A complete assembly, consisting of an artillery tube and a breech mechanism, firing mechanism or base cap, which is a component of a gun, howitzer or mortar. It may include muzzle appendages.
- Any similar device for shooting material out of a tube.
- A bone of a horse's leg, between the fetlock joint and the knee or hock.
- A cannon bit.
- A large muzzle-loading artillery piece.
- A carom.
- The arm of a player that can throw well.
- A hollow cylindrical piece carried by a revolving shaft, on which it may, however, revolve independently.
- (Chinese chess) A piece which moves horizontally and vertically like a rook but captures another piece by jumping over a different piece in the line of attack.
- To bombard with cannons.
- To play the carom billiard shot. To strike two balls with the cue ball
- To fire something, especially spherical, rapidly.
- To collide or strike violently, especially so as to glance off or rebound.
- A generally accepted principle; a rule.
- A group of literary works that are generally accepted as representing a field.
- The works of a writer that have been accepted as authentic.
- A eucharistic prayer, particularly the Roman Canon.
- A religious law or body of law decreed by the church.
- A catalogue of saints acknowledged and canonized in the Roman Catholic Church.
- In monasteries, a book containing the rules of a religious order.
- A member of a cathedral chapter; one who possesses a prebend in a cathedral or collegiate church.
- A piece of music in which the same melody is played by different voices, but beginning at different times; a round.
- (Roman law) A rent or stipend payable at some regular time, generally annual, e.g., canon frumentarius
- Those sources, especially including literary works, which are considered part of the main continuity regarding a given fictional universe.
- A rolled and filleted loin of meat; also called cannon.
- A large size of type formerly used for printing the church canons, standardized as 48-point.
- The part of a bell by which it is suspended; the ear or shank of a bell.
- A carom.
- A clergy member serving a cathedral or collegiate church.
- A canon regular, a member of any of several Roman Catholic religious orders.
- A Near Eastern and Caucasian musical instrument related to the zither, dulcimer, or harp having either 26 strings and a single bridge, or twice that number and two bridges.