$.each(response, function(index) {
    $('#myID').append('<tr><td onclick="select(this)" >'+ response[index] +'</td></tr>');
});

function select(element){
...
}

function select(element){
  var elem = $(element);
  if(elem.hasClass("active")) {  // is ajax call active?
    return false;
  }
  elem.addClass("active");  // set it that it is active
  $.ajax({
    url: "foo"
  })
    .done(function(){})
    .always(function(){
      elem.removeClass("active");  // call is done, so remove active state
    })
}

function select(element){
    $(element).prop('disabled', true);
    $.ajax({
        url'url',
        success:function(response){
            $(element).prop('disabled', false);
        }
    });
}