LST is low stress training. You tie down the stalk (don't forget to tie an anchor or you'll rip your lady out) exposing it to the light. This allows to have more than one cola. If you do a search, there is a lot of info and pics on the practice. You can still do it even though you topped. Just another way to get more bud from one plant! And your clone is looking good...what are the temps in there?