Edit in JSFiddle

<p class="modIcnTxt modIcnTxt-withIndent"><a href="#">ダミーテキストダミーテキストダミー<br>テキストダミーテキスト</a></p>

<p>お問い合わせは <a href="#" class="modIcnTxt">こちら</a> からお願い致します。</p>
.modIcnTxt.modIcnTxt-withIndent {
  padding-left: 10px;
  text-indent: -10px;
}
.modIcnTxt:before {
  position: relative;
  top: -0.1em;
  display: inline-block;
  content: "";
  width: 5px;
  height: 10px;
  background: transparent url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAKCAYAAAB8OZQwAAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5ccllPAAAAEpJREFUeNpiMDExEfz//z8DMmZiYGB4Z2pqWs6ABJigdAeyBBOSArgEI9DM/wyooIKJAQtAF6w4ffp0JxO6ALJKuAAYYHM8QIABAHw5Kstvzw3RAAAAAElFTkSuQmCC) no-repeat;
  vertical-align: middle;
  margin-right: 5px;
}

a.modIcnTxt, .modIcnTxt a {
  text-decoration: underline;
  color: #000;
}
a.modIcnTxt:hover, .modIcnTxt a:hover {
  text-decoration: none;
}