Grefter's idea is valid. A few other suggestions:
- I can't remember if Cloud's AI is set to retreat intelligently or not there, but if it is, giving him a turn from Cheer Up (Ramza's Guts) or Quick (Time Magic) could get him out of dodge.
- Status the most problematic unit out next to him ASAP (Talk Skill, Yin Yang). The Monks and Mimes shouldn't have any particular resistance to status. Casting Blind is unironically good because it will double Cloud's evasion from Feather Mantle, and has longer range than most status spells.
- If Protect would ward off the OHKO on Cloud, you could try setting that up on him before he gets attacked. Kiyomori from Draw Out works as an instant option. This strategy will require you to keep him healed up in general though, favoring all-out keeping him alive.
- If getting in range is an issue in general, consider Teleport, or just high move setups (Ninja, Move+2, Germinas, Brigandine, etc.)