Buying people stuff for hobbies you know they're into sounds great, but the thing with gear of something you're an enthusiast in is that you know your needs and preferences, and other people don't. Unless she's told you "this is my dream putter" or something, there's a good chance you'll get something she doesn't really want and might feel obligated to use.
Exceptions are things like lessons if you know they want them, books on the subject, maybe, or a well researched starter kit for a hobby you know they haven't actually started but want to explore. But most other stuff, they have their own preferences on. Either talk details, or think about doing something different, IMO.
I don't know a lot about golf specifically, but it's an answer I've seen elsewhere on similar discussions, and it's rung true every time I've been on the receiving end for hobbies I am more engaged with.
It's a great sentiment, and shows you know them, and all of that, and it's appreciated from that perspective. But it's usually hard to find a use for stuff someone less interested picked out.
I'd say the other exception I probably missed is when you're the expert way ahead of the recipient. That's a case where you have the knowledge to give them something they wouldn't buy themselves but can benefit from.