It's great that you took this budgie in.
Your budgies doesn't have to be tame to be happy. Nor does it need to have a budgie friend, but it might help if you don't have the time to dedicate to him.
You would probably be best getting him a little male friend. This would give him a bird companion but would save you the worry of breeding.
It might be that he would welcome a bird friend, but he could also be used to being alone, so you could have to keep them in a cage each.
I don't believe clipping his wings will help in any way to calm this poor budgie.
Have you tried steps to create a bond with him? If not, try treating him like a brand new budgie. If he still gets easily spooked (and I wouldn't be surprised considering what happened) cover three sides of his cage. This will help him feel safe.
Spend time sitting by his cage and talking softly to him.
You can also leave the TV or music on for him so he won't feel frightened (silence means danger to budgies).
If he seems to be calm after about a week of talking to him, I would then try to place your hand on the cage while you talk to him. Again, try this for a week and see if he gets used to it.
If he gets used to this, he should calm down when you start to clean his cage out.
I hope this helps and I'm sure others will have some great advise as well.