Dangerous rock on Italian coast (6)
I believe the answer is:
scylla
(Other definitions for scylla that I've seen before include "Charybdis counterpart" , "Six-headed monster who sat on a rock opposite Charybdis" , "Female sea monster in Greek myth, lived opposite whirlpool Charybdis" , "legendary menace in Med" , "Peril with Charybdis" .)