Previous owner cut out ribs that hold down lip of battery. They put in a bigger battery and it would only fit with ribs cut out. Battery they used is. Also 1.5” taller. So, cover does not fit. And clamp is missing. Only way to really fix this is get a new battery box?
Pic 1 shows ribs/lip that holds down battery and pic 2 shows ribs cut out. No easy way to add a generic hold down. Grab a box at junkyard.
Can’t really see but gee if you can just get a new box, why not. I don’t remember which car but I bought a new metal tray from the dealer very cheap. Either that or just improvise a repair or use the larger battery.
Did the oversized battery move around any, or was it a tight fit?? And if you had hood clearance, I personally would not worry about it and just use the bigger battery… Maybe run a bungee cord around the box somehow…
But yes if you want it done to spec, try a junkyard…
That’s what I was thinking. The pics are hard to go by and we don’t know what the vehicle is, but yeah. Just go grab a used one from a pick n pull.
Or go old grandpaw (yes I know that is most of us lol) school and cut down some wood to fill in the gap and run with it… 
One side of battery is wedged under ribs/lip and other side is held by wedge clamp. The clamp was gone too. So, battery was just bouncing around. And cover holds the pcm so that was bouncing off inside of hood. Guess seller really wanted to use the big battery I now have. Battery shop just laughed when I told them what size it was. They said no way it would fit. “Well”. With a little cutting? No problem
My mower uses a motorcycle battery at about $70 rather than the $25 lawn and garden battery you see pallets of them everywhere. Considered modifying the cradle to use cheaper but larger battery but decided it wasn’t worth it.
Just go get a new box like I said. Either junk yard or dealer.
I got another battery box. Battery is secure. And a bit less noise.