I lost a button from my suit.
If your back is wide, you need a nice business suit to cover it up when you go to work. Otherwise you'll look completely out of place sitting at a desk like a giant, wide-backed wrestler. Is that what you want to look like? Of course not! You need to go out and buy a fancy suit to cover your wide back up right now!
The readings for this word are both kun'yomi readings. You've learned them both already so you should be able to read this too! Just watch out for the weird rendaku here making it び not ひ.