When do you clean a photo? (With an example)

[Jobu]

I am new to collecting photos and am trying figure out what to do with the photo below, a picture of Mickey Mantle on his first pro team, the semi-pro Whiz Kids, from 1947 when he was 16 years old. Mantle and a few of the other players have signed the picture (the other sigs are barely legible).

The condition is a bit rough because it is an original that belonged to one of the kids in the picture, Guy Crow, who was the bat boy (left end of the right bench).

I don't think I am interested in having the missing parts restored as I see the condition as part of the history. I am worried that the dirt and stuff on it might not be good for the picture over time ... not to mention the smudges also obscure the image a bit.

Is having it professionally cleaned an acceptable thing to do? If so, is it really costly?

Thanks in advance.