Golfers do not like to hear the word “shank” or “hosel rocket” as it is also called.  When we see it or experience it.........Ouch! 
The dreaded shank is sometimes compared to a split in bowling. It is fractions away from a well-executed shot.  It seems we pay an awful penalty for a nearly perfect move.   What causes the shank? I say that poor posture in the set up and a swing from the outside in will do it.  Let’s cure it. 
First, strike a ready athletic position as you address the ball.  In many other sports (tennis, baseball, bowling, for example) you must be ready and relaxed (focused and free).
Posture is critical.  Check your hands.   They must hang in front of your knees a little away from you – not by or straight over them.  Check your weight. It must be in the middle of the arches of your feet, not on your toes or heels. There must be flexion in the knees, but not too much.  Look down at your feet.  If you do not see any part of your shoes, your knees are bent too much.  If you see most of your shoes, your knees are too straight. With the correct amount of flexion, you should see a little less than half of your shoes.  Now lift your rear end, keeping your lower back straight.  Your head (chin) should be forward and slightly up, not down toward your chest. Your spine and your center of gravity will be properly positioned for you to release the club correctly.
Practice your set up in front of a mirror.  Take a practice swing slowly and monitor your hand position through your release.  Repeat and repeat and repeat.
A good drill to make sure that you are not coming from the outside in is to place an object (your glove or head cover will do) just outside the ball and make swings down from the inside.  You can kiss the shank goodbye.  You have killed the monster!!!!!!!!!