The published minimum connection time (MCT) in CLT for an international-to-domestic connection is one hour. Assuming you are flying on AA FCO-CLT-xxx, then since your connection is more than the MCT, AA is obligated to reaccommodate you in case you miss your connecting flight. MCT is an official estimate of how much time is safe under normal circumstances.
If your FCO-CLT flight is late, AA might proactively rebook your connecting flight, and/or might meet you as you get off the flight in CLT and hand you an orange "expedited connection" card (to let you cut long lines) and/or a new boarding pass for a different connecting flight. (In some cases, they might "protect" you by booking you on a later connecting flight in addition to your original flight, but more commonly your connecting flight is changed.)
If there are long lines to clear Immigration or Customs in CLT but you still have a chance to make your flight, assuming you have your connecting flight's boarding pass, proceed directly to the security checkpoint (don't stop at the AA check-in desk) and then to your departure gate. If you get to your departure gate too late, if there's still an agent there, he or she can reaccommodate you on a different flight. If there is no agent, then if you have an Admiral's Club membership, go to the Admiral's Club and ask an agent there to help you.
If it's obvious you won't make the flight, then go to the AA check-in counter before security. If there is a long line there, also call AA reservations while waiting in line. You will need to be reaccommodated on a different flight.