How to select option selected?

        <div class="item item-input item-select">    
            <span style="padding-left:0" class="input-label"> Account No. </span>
            <select ng-model="sa.item" ng-change="update(sa)">
              <option value="" ng-selected="selected">-Select One-</option>
                    <option ng-repeat="x in stopChequeAccountListNodes" >{{x.accountNum}}</option>

I have dropdown list above populated from database. I have a clear button. when i click on clear button then it goes -Select One-. That means it selected -Select One- option.

How to do it?

Please Help me…