A class, archetype or whatever will specify free prerequisites. For example, the Dawnflower Bard gives Weapon Finesse free along with Dervish Dance at first Level.
The Slum Spirit does no such thing.
There isn’t even a feat for Uncanny Dodge. You could take a couple levels of Barbarian or Bloodrager. But usually multi-classing is a no-no.
If it isn’t granted then it is up to you and your GM. If this is PFS, then you are probably out of luck.
It appears that you would not have Uncanny Dodge. So you could be caught flat-footed and lose dexterity bonuses to invisible creatures, but you could not be flanked and a rogue could not use sneak attack unless they had at least four more levels in rogue than you have in shaman.