Answer: trephine

AnswerCrossword Clue
TREPHINESurgical saw
trephinesmall circular saw with a center pin mounted on a strong hollow metal shaft to which is attached a transverse handle: used in surgery to remove circular disks of bone from the skull
trephineto operate upon with a trephine
trephineto operate on with a surgical saw, also TREPAN, TRAPAN