Possible Clues:

• Using weapons in game, finally attempt to get on scent
• Skill never performed by 15-Across, oddly enough
• Shooting deer, shot holding end of rifle
• The Guardian finally kick the bucket: editor held in compiler's arms
• Think to protect king — experiment with small arms
• Old guns sum up last half of joke ¿ it gets the crowd going at Aviva
• Armed soldiers encountered spanning river with railway