When looking to "make" the selected item, it is commonly understood as setting it. Here is one way to achieve this, although there may be alternative methods.
To set the [attr.selected] in the option tag:
<select class="form-control" name="Underwriter">
<option *ngFor="let underwriter of policyModel?.underwriterList" [ngValue]="underwriter.value" [attr.selected]="underwriter.text === underwriterTextString ? true : null">{{underwriter.text}}</option>
</select>
In your code, ensure that you assign a value to underwriterTextString when the WebService API provides a response.
If underwriter.text does not yield the desired results, consider using underwriter.value.
However, if your objective now is to "get" the selected item, you can utilize the change event within the select tag:
<select class="form-control" (change)="onChangeunderwriter($event)" name="Underwriter">
<option *ngFor="let underwriter of policyModel?.underwriterList" [ngValue]="underwriter.value" [attr.selected]="underwriter.text === underwriterTextString ? true : null">{{underwriter.text}}</option>
</select>
Your code should include something like this:
onChangeunderwriter(event) {
//the value will be set in event.target.value;
}