Front end clunking noise

Turned a corner and heard a clunking noise from front end driver's side. Pulled in my drive way and put it in reverse to see if I could hear noise and I had to give it quite a bit of gas to get it to move. Pulled forward fine but it was clunking in reverse. It felt as if emergency break was on. Jacked it up driver front tire will move forward but not backwards with engine off in park and in neutral. Big problems or could I be fortunate and it be a small fix? Thanks for your time.