What's a "golfclap"?

An old friend of mine, some years ago, was a K1 Cook with 45 Commando RM during their deployment in Aden and Borneo in the 60s - he actually was the champion machine gunner and would often (in Aden) spend the nights on ambush duty and the days cooking for his Comapny. Sadly, given 45's base at Arbroath, he wasn't a jock but an Englishman - but a braw lad for a' that!