:Tab /\S\s\zs[ ]\S*
Explanation: \S\s* finds a non whitespace character followed by as many whitespace characters as possible. This brings us to the beginning of the variable name. We then use \zs which says that the "found" area should only begin here.
Since we want the * in block_style to be attached to the indented word but not before the variable name, we match either * or space followed by a non-whitespace character to symbolize the beginning of the word. End result: