Q. A player breaks the shaft of his 4-iron when the follow-through of his stroke causes the shaft to make contact with the trunk of a tree. May the player replace the club during his round?
Yes, the player may replace the club -- see Rule 4-3.
The player's club is unfit for play and this occurred during the normal course of play (see Decision 4-3/1).
The broken club may be replaced provided the player does not unduly delay play and provided he does not replace the club by borrowing a club selected for play by any other person playing on the course.
The player does not need to replace the broken 4-iron with another 4-iron; he may replace it with any conforming club.
Below you can view videos related to this Rule.
Carrying 15 clubs
At the 2001 British Open, final round co-leader Ian Woosnam's frustration bubbled over on the second tee when he discovered he was carrying 15 clubs when only allowed 14.