What? Seriously. First of all, 4th job is a Bishop, not a Cleric, and Bishops are a different animal. Use Genesis on the arms (hitting all eight at once ftw), then maybe Angel Ray if you wanted to save MP on the body, except during summons, which would be Genesis again. You wouldn't get mad damage because Zakum's not holy-weak, but you could still do it eventually. You'd even have better mob control than a DK, as weird as that sounds. xD
Geez. Bishops aren't /that/ weak. >>;