Definition: Club-Length
The length of the longest club of the 14 (or fewer) clubs the player has during the round (as allowed by Rule 4.1b(1)), other than a putter.A club-length is a unit of measurement used in defining the player's teeing area on each hole and in determining the size of the player's relief area when taking relief under a Rule.
For the purpose of measuring these areas, the length of the entire club is used, starting at the toe of the club and ending at the butt end of the grip. But any attachment to the end of the grip is not part of the club-length.
[+] Club-Length/1 - How to Measure When Longest Club Breaks