The answer to this is 出来る but I thought this was to be ready to do / to be ready for? The hint is “A verb indicating the ability or capability to do something.” so this didn’t make sense
This is another meaning of 出来る meaning to appear or form. Often used when talking about some sort of bump appearing on an otherwise flat surface (welt, acne, etc). You’ll run into this meaning occasionally, so best to know about it! 
You’re right about the hint being weird for this one though since it’s not the most common usage of the word
2 Likes
I think of 出来る as “The ability for something to come out right”
So for being possible, its expressing the ability for the action to (be possible to) turn out in that manner, and for a bump its the same for it to “turn out” to “come out” right.
I think turn out and come out sort of share similarities of how we think of them in English. A welt can “come out” and a painting can “come out” alright as well. It is definitely not one to one but it is how I think about it.
出来る is a self move verb, intransitive, so I think that is the key to the issue, we say “I can do __” but in Japanese it’s intransitive.