I presume you are not using an 11-speed rear derailleur. Is that right or wrong?
When Campagnolo went from 9-speed to 10-speed, the inner cage was modified to achieve more spoke clearance ...
So, consider this:
- take the inner cage off
- incrementally file down the top edge & round the top edge with a ~60º bevel
- re-install
- check for clearance
Repeat until clearance is achieved.
Clearance may NEVER be achieved with some wheels; so,
before you actually do any surgery on your rear derailleur simply detach the inner cage from the upper pulley and see how much-or-little clearance exists & ascertain if there will be enough material left around the bolt if you do remove (file away) the 'excess'.
If you are using a 10-speed rear derailleur & don't want to work on it, then you may have to pony up for a new, 11-speed rear derailleur OR at least a new, 11-speed inner cage.