Golf clubs attract their own fee. The Ryanair website holds all the answers to all your luggage- and fee-related questions. You have the option to add non-standard luggage: sports equipment/skis/bikes/golf clubs/musical instruments/prams etc as part of the online ticket purchase flow. DO NOT ADD LUGGAGE IF YOUR "LUGGAGE" IS ONE OF THESE SPECIAL ITEMS, SCROLL DOWN AND ADD THE APPROPRIATE EXTRA ITEM INSTEAD. Luggage only refers to standard bags of the acceptable dimensions and weights, and you cannot check a Golf Bag in as a paid "regular" luggage. You cannot "substitute" a paid normal luggage allowance (whether paid separately, or bundled into your fare) for something that has its own, separate charge.