an arrow shot from ambush is something difficult to guard against.; a covert attack is hard to avoid.; a stab in the back or a sneak attack is not for one to forestall.; hidden arrows are difficult to guard against.; it is hard to parry [ward off] a snipper's arrow
Related Translations:
暗箭: (暗中放箭, 暗中陷害人的行为) an arrow shot from hiding; a stab in the back; attack by a hidden enemy; secret activities designed to hurt sb.; a sneak attack
谨防暗箭: guard against a hidden arrow -- to take precautions against a covert attack
放暗箭: stab (sb.) in the back; attack sb. with unfriendly remarks behind his back; snipe (at sb.)