What exactly does "1st play" mean on the achievements list?

[Mr. Toothpick]

Hey there,
I was replaying this game and thought I would try for some of the achievements when I noticed some of them specify "1st play." What exactly does this mean?
For example, one achievement says "defeat 80 enemies while using the power gear (1st play).
Does this mean I need to start a whole new playthrough to get this achievement or can I go into one of my older save files and farm for it that way? I already finished the game twice, so can I just hop back into one of those files?
Thanks in advance!

[Make]

1st Play means when you choose New Game from the title screen instead of loading a "Clear Save".

As you know, once you beat a game, you get to save your data (Clear Save).