An example will be most specific:

 func[list_, column_] := list[[All, column]] = Map[#*2 &, list[[All, column]]];

This throws errors.

I want to avoid doing something like this:
 
 func2[list_] := Map[#*2 &; list];
 list[[All, 2]] = func2[list[[All,2]]]

because nesting a couple of functions raises complexity unnecessarily, the output would have to be reassigned every time.

Thanks in advance