Here is another Tk version, :-) Mine differs in style from BrowserUk's. He made a bunch of pie segments to manipulate. I used a technique of layering an arc over a background circle, and changing their extent and color. There are many ways to do it!

UPDATE: added 'cleanup' tags to improve performance, and fixed the bell repitition problem.

#!/usr/bin/perl
use warnings;
use strict;
use Tk;

my $mw = tkinit;

$mw->fontCreate('big',
   -family=>'arial',
   -weight=>'bold',
   -size=>int(-18*18/14));

my $running = 0;
my $canvas = $mw->Canvas(-width => 600, -height => 600,
                         -bg =>'black')->pack();

my $start_message = $canvas->createText(300,30,
               -text   => 'Press SpaceBar to Start',
               -fill   => 'hotpink',
           -anchor => 'center',
               -font   => 'big');

$mw->bind('<space>', \&start );

MainLoop;
###########################################################

sub start{
 return if $running;
 $running = 1;
  
 $canvas->delete('cleanup'); 

 $canvas->itemconfigure($start_message, -state => 'hidden');
 
 $canvas->createOval(100,100,500,500, 
                -fill => 'white',
        -tags => ['backplate','cleanup'],
        );

 my $extent = -1;
 my $arc = $canvas->createArc(100,100,500,500, 
                          -extent => $extent,
                          -start => 90,
              -fill => 'black',
                          -tags => ['cleanup'],
                 );

 my $repeater;
 $repeater = $mw->repeat(20, sub{
                  $extent = $extent - 1;
                  $canvas->itemconfigure($arc, -extent => $extent);
                          
          if( $extent == -320 ){
               print chr(07); #beep
              $canvas->itemconfigure('backplate', -fill => 'red');
                }
                  
          if( $extent < -359 ){
              $repeater->cancel;
              &message;
                }
          
          });
}
##############################################
sub message{

      $canvas->createText(300,300,
               -text   => time,
               -anchor => 'center',
               -font   => 'big',
              -tags => ['cleanup'], 
              );

   $running = 0;
   $canvas->itemconfigure($start_message, -state => 'normal');
}
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