Rule 5.2b: A player must not practice on the course before a round, EXCEPT: A player may practice putting or chipping on or near his or her first teeing area and on any practice area.
Rule 4.3a(6): During play, use of any type of golf training or swing aid (such as an alignment rod or weighted headcover or “donut”) or a non-conforming club to make a practice swing or in any way that creates a potential advantage by helping the player in preparing for or making a stroke is NOT ALLOWED. Julie Inkster used a weighted club during an event and was disqualified.
Rule 5.5a: No Practice strokes while playing Hole. While playing a hole, a player must not make a practice stroke at any ball on or off the course. Perfectly ok to clear out range balls with a club to “clean up” the course (such as #18) as long as you are not practicing hitting a ball (taking a stance, lining up, etc.)