Menus don't have to be logic they have to be meaning and useful.
If there is one "child" then you do not need a "parent" like a unique radio button does not make sense.
Having sub-navigation on-click is common but very replaceable
Most web sites do not have sub-navigation menus. A book of one chapter does not need a summary: you just read it, a house with one room does not need a plan: you just enter.
That said: if there is a drop-down menu, then clicking on the "parent" usually opens the drop-down and does not lead to another page. If it is a hover menu, usually the "parent" is not clickable or it makes everything confusing.
Design the web site structure before building the menu should help avoiding this kind of problem. * Remember A website is not a taxonomic table.*
You can deal with exceptions by treating them as exceptions though :
download bmml source – Wireframes created with Balsamiq Mockups
I guess if an entity has its own class then it might be enough important to be in the menu.
If not :
download bmml source
It is quite ambiguous to use the term intuitive
I found a definition in Klaus B. Bærentsen, INTUITIVE USER INTERFACES
An intuitive interface may be defined as an interface, which is
immediately understandable to all users, without the need neither for
special knowledge by the user nor for the initiation of special
educational measures. Anybody can walk up to the system; see what kind
of services it affords, and what should be done in order to operate
it. While operating the device, navigation and manipulation of the
system interface should proceed without the need for conscious
awareness of the sensory- motor operational aspects of the interface
We are not at all in this kind of situation since the users uses it former knowledge in classes and fields to find what he wants.