Yes, there is. Simply include the recursesubdirs flag to your [Files] section entry. The help says about this flag the following:
Instructs the compiler or Setup to also search for the Source
filename/wildcard in subdirectories under the Source directory.
So, all you should do is modify your [Files] section entry this way:
[Files]
Source: "..\Tcl\*"; DestDir: "{app}\Tcl"; Flags: ignoreversion recursesubdirs