There is a band aid of sorts that can work to help with a slice while you are the course, with no practice shots a available to you. It has been around for as long as I can remember, and I think Hogan even made a partial reference to it in one of his books.

Align your body (knees, hips, shoulders) square (parallel) to your target line. Once your stance, and alignment is taken, flare your lead foot out towards your target an inch or so. then move your rear foot straight back from your target line about a inch, but turn your big toe in towards your target a little. Don't move anything else but the feet. Then, take your normal swing. A few adjustment might be in order due to individuals' swings.

I don't know why this works, but it does, and I have seen it work for the better many times on the golf course after showing it to someone with a slice problem. Sometimes when I get tired with a few holes to go, I use this set up to help keep the ball flying reasonably straight off the tee. It seems to work better with the longer clubs.

Again, this is only a band aid untill the real swing problem can be identified, and worked out. GJS