Thanks for your help Noah, I ended up asking my web-guru friend who gave me this genius answer, assign a class to it and then you can control it through CSS eg.
function addFeatureLayer() {
var featureLayer = new FeatureLayer("http://services.arcgis.com/7eMCKfEPV8BkFVLQ/arcgis/rest/services/PubsFaceWatch/FeatureServer/0", {
id:"featureLayer",
styling:false,
dataAttributes:["Incidents"]
});
console.log(featureLayer);
if (featureLayer.surfaceType === "svg") {
on(featureLayer, "graphic-draw", function (evt) {
className = "svgClass";
// set the data attribute for the current feature
evt.node.setAttribute("data-class", className);
});
} else {
alert("Your browser does not support SVG.\nPlease user a modern web browser that supports SVG.");
dom.byId("legend").innerHTML = "Your browser does not support SVG.";
}
map.addLayer(featureLayer);
return featureLayer;