2 "s" needs no quotes. But I had forgotten the modulo.
source | link

PHP, 104104 105 bytes

<? for(;;sleep(6))printf("%'
99s%2d %'-".($m=date(i))."s
%2d %'-".(60-$m)."s"s,"",$h=date(H),"",++$h++$h%24,"");

showcase for printf´s custom padding characters:
"%'-Ns"=left pad string with - to N characters.

will print 99 newlines (every 6 seconds) instead of clearing the screen.

First newline must be a single character. So, on Windows, it must be replaced with \n.

PHP, 104 bytes

<? for(;;sleep(6))printf("%'
99s%2d %'-".($m=date(i))."s
%2d %'-".(60-$m)."s","",$h=date(H),"",++$h,"");

showcase for printf´s custom padding characters:
"%'-Ns"=left pad string with - to N characters.

will print 99 newlines (every 6 seconds) instead of clearing the screen.

First newline must be a single character. So, on Windows, it must be replaced with \n.

PHP, 104 105 bytes

<? for(;;sleep(6))printf("%'
99s%2d %'-".($m=date(i))."s
%2d %'-".(60-$m).s,"",$h=date(H),"",++$h%24,"");

showcase for printf´s custom padding characters:
"%'-Ns"=left pad string with - to N characters.

will print 99 newlines (every 6 seconds) instead of clearing the screen.

First newline must be a single character. So, on Windows, it must be replaced with \n.

1
source | link

PHP, 104 bytes

<? for(;;sleep(6))printf("%'
99s%2d %'-".($m=date(i))."s
%2d %'-".(60-$m)."s","",$h=date(H),"",++$h,"");

showcase for printf´s custom padding characters:
"%'-Ns"=left pad string with - to N characters.

will print 99 newlines (every 6 seconds) instead of clearing the screen.

First newline must be a single character. So, on Windows, it must be replaced with \n.