$fields→clone() 
Create and return a cloned copy of the given Field
Usage
// basic usage
$field = $fields->clone(Field $item);
// usage with all arguments
$field = $fields->clone(Field $item, string $name = '');Arguments
| Name | Type(s) | Description | 
|---|---|---|
$item | Field | Field to clone  | 
$name (optional) | string | Optionally specify name for new cloned item  | 
Return value
Field$item Returns the new clone on success, or false on failure
Hooking $fields→clone(…)
You can add your own hook events that are executed either before or after the $fields method is executed. Examples of both are included below. A good place for hook code such as this is in your /site/ready.php file.
Hooking before
The 'before' hooks are called immediately before each $fields method call is executed. This type of hook is especially useful for modifying arguments before they are sent to the method.
$this->addHookBefore('Fields::clone', function(HookEvent $event) {
  // Get the object the event occurred on, if needed
  $fields = $event->object;
  // Get values of arguments sent to hook (and optionally modify them)
  $item = $event->arguments(0);
  $name = $event->arguments(1);
  /* Your code here, perhaps modifying arguments */
  // Populate back arguments (if you have modified them)
  $event->arguments(0, $item);
  $event->arguments(1, $name);
});Hooking after
The 'after' hooks are called immediately after each $fields method call is executed. This type of hook is especially useful for modifying the value that was returned by the method call.
$this->addHookAfter('Fields::clone', function(HookEvent $event) {
  // Get the object the event occurred on, if needed
  $fields = $event->object;
  // An 'after' hook can retrieve and/or modify the return value
  $return = $event->return;
  // Get values of arguments sent to hook (if needed)
  $item = $event->arguments(0);
  $name = $event->arguments(1);
  /* Your code here, perhaps modifying the return value */
  // Populate back return value, if you have modified it
  $event->return = $return;
});$fields methods and properties
API reference based on ProcessWire core version 3.0.252