You ned to use Javascript to display clock at page. You can use any of it, just goole and select clock you like. For example this from w3schools it will display clock in the user's current timezone.
If you still want to show clock in predefined timezone just set starting values from PHP instead this line from above example:
var today=new Date();
use something like
var today=new Date(<?=$current_timestamp_in_selected_timezone?>);
Use PHP function to build $current_timestamp_in_selected_timezone
mktime()
or date()
Note that you need to write javascript code inside your View
to use such technic what isn't a good approach. In good application you need to write code of your JS clock in JS file, put it into app/webroot/js
, include that file in layout or call inside controller and than pass variable from PHP. How to do that read here: How to pass variables and data from PHP to JavaScript?