If a golf club strikes the ball out of the centre of the club face
with the club path on the target line through impact, and the face
square to target, the ball will move towards the target with no
If the same shot is played but the impact is towards the toe of the
club, the club face will open slightly as a result, and side spin will
Not entirely the case.
Although the tendency is for the face to open slightly as a result of impact toward the toe of the club, it is still possible to have the face square to target, meaning the ball will still move towards the target with no side-spin...albeit less backspin (and possibly less distance) because the ball didn't squarely make contact with the grooves, which is responsible for generating optimum spin.
Consider how forgiving drivers are with their massive sweet spots. A shot in which impact is off-center will still produce a similar shot to a shot in which impact is on-center, all things equal.
AJ Bonar of The Truth About Golf(1) presents the following suggestion as physics-based. As you are more versed in physics than I am, I suggest examining this approach.
Disclaimer: I do not endorse Bonar's approach. In fact, I was bored from "The Truth About Golf" and didn't watch the entire instruction. However, I found his following suggestion to be helpful to my golf game.
Bonar suggests that the direction the grooves are facing, not the direction of the clubface (open/closed), is the primary factor.
Ever open/close your stance, hit a shot in which the swing path is parallel to your stance, and end up hitting the shot toward the line of your stance? This is because: 1) Your stance lined up in that direction. 2) The grooves were parallel to the ground when you made impact with the ball. Thus, resulting in a straight shot to the direction in which your stance was opened/closed.
Consider your address position. If you are standing too far away from the ball and make solid impact with the ball, what is the ball doing? The ball is most likely drawing because the grooves were leaning toward you at impact. Now, if you are standing too close to the ball, the ball is most likely fading because the grooves were leaning away from you at impact.
The best illustration I can think of is of a golfer going "over-the-top." Notice on the downswing how upright the club had become from address as a result of going over-the-top. The result from here is a slice or push-slice as the grooves were leaning away from the golfer at impact.
for a right handed golfer is the spin clockwise (ball path bends
right) or anti-clockwise (ball path bends left).
Based on my last few paragraphs, this depends on what direction your grooves are facing at impact. If your grooves are leaning toward you, the ball is spinning counter-clockwise (ball is drawing/hooking or bending left). If your grooves are leaning away from you, the ball is spinning clockwise (ball is fading/slicing or bending right). If your grooves are parallel to the ground at impact, there is no side-spin.
NOTE: My answer is based on the right-handed golfer.
I have played golf for 15+ years, came across this several years ago, and came away with a better understanding of how to draw/fade shots.