clean it really well and then I'd put some type of bonding agent on the outside, I've had to superglue a cracked beak before, have two people. one holding the hen wrapped in a towel under one arm, the other arm holding her head. person #2 hold the beak open, pinch beak firmly with thumb and forefinger, to hold her still and keep her beak open. Then just use a q-tip to apply a tiny dab, and make sure your holding her mouth open for a minute for the glue to dry. then you shouldn't have to worry about it.
if its only a small crack on the corner of the beak, no blood etc then just take a finger nail clipper and clip the edges of the beak off, usually the 'dead' bit of beak is a lighter color than the rest of the beak it (like our fingernails - ends are dead the rest is tender and can bleed when nicked) and file the edges a bit with a nail file or dremel tool. this will take the edged end off the crack, and make it unlikely the crack will get any worse. it should heal just fine with no issues.
