Here's a PICO for a nurse mentoring problem. I didn't put much time into it but it might give you a starting point.
Research Question: Will the development of a new graduate nurse mentoring program improve outcomes in (pick an area; retention of new grads, rate of med errors, patient satisfaction, etc)
P- Population or Problem: New graduate nurses on a particular unit.
I- Intervention: Creation of a cadre of experience nurses who will mentor newly graduated RNs
C- Control: choose 2 similar units in the same hospital, i.e. 2 med/surg floors; implement the program on one floor but not the other
O- Outcome: measure your choice from the question, retention rate, med error rate, patient satisfaction, before and after on both the test unit and the control unit.