First let me say I am not a photographer, however I have a photo that was taken of my mom, myself and niece that is very dear to me. The photo was not properly focused I don't think. Could a professional improve the focus? I would love to enlarge and frame it.
Professional photographers can do wonders, though the skill level in photoshop varies fairly widely among the group. Finding one with the right skill set will be your challenge.
That being said, photographers typically stop right after manipulation - they don’t typically add things that weren’t there. In your out of focus shot, you have details missing due to the focus.
A graphic artist may be able to take things a step further by adding back those lost details.
This better be one heck of a sentimental photo though, because either option above is going to cost a bit.