So, its a 4-5-1 giving the wingers license to go forward due to the extra man in midfield.
It's a 4-3-3 if the starting position is that your focus is on being involved in the attack but mindful of backing up when necessary. 4-5-1 would suggest your first thought is to be held back in midfield. Personally I think we should call it a 4-3-2-1 in true FM fashion, everyone understand's their formations this way now.