http://api.jqueryui.com/clip-effect/ documentation specifies the following settings for the clip effect:

However, up should be both according to http://code.jquery.com/ui/1.12.1/jquery-ui.js:

var effectsEffectClip = $.effects.define( "clip", "hide", function( options, done ) {
	var start,
		animate = {},
		element = $( this ),
		direction = options.direction || "vertical",
		both = direction === "both",
		horizontal = both || direction === "horizontal",
		vertical = both || direction === "vertical";