It's a flaw of ten months which apparently need not be fixed. :(
User's workaround:
- enter "Change Equipment",
- disregard the faulty club,
- equip and unequip other clubs until the SAVE button becomes green,
- SAVE whatever you have,
- leave the equipment section and re-enter (this might be dispensable),
- enter "Change Equipment" again and set up the clubs that you want.
Have fun!