Hi OP I have worked as a journalist most of my life, apart from a break when I was a teacher. Newspapers, magazines and PR tho rather than broadcast.
I want to put a different viewpoint. PPs have mentioned journalists whose degrees are in other subjects - mine is in MFL FWIW. Thing is tho, I would say that mainstream availability of degrees in journalism only dates back (guessing here) say 15 years? So the majority of journalists had no chance of taking that degree. Certainly it was not an option for me in any way.
That said, it is of course possible to become a journalist with doing a journalism degree. I am in no way a fan of the idea of a degree in journalism in general - how on earth do students spend three years studying it? and at the end so many of them still cannot write in decent English. But I do think it is a more straightforward way into the career if that is definitely what you want. The degree at Derby, to take an example, is very well taught by lots of former journalists and involves a lot of hands-on practical work and experience.
But if your DD is able enough to study and enjoy studying (for example) French at Bristol or PPE at Oxford or economics at Durham, then that might be a better choice with more options at the end of her degree. Journalism degrees IME tend to be offered at less popular unis. If she can flourish at a higher-ranked uni then that may be a better choice.
This is the thing though; the most most important thing is that she is writing and publishing her writing. Does she write a blog? Has she done some work on the local hospital radio? Could she start a radio station at lunchtimes in her school? These are the kinds of things future editors will be expecting and be impressed by. Why broadcast especially? Does she want to be Andrew Marr or is there a more viable reason? Can she articulate that and then see what might help lead to it - work exp at the local BBC radio station, setting up her own YouTube channel locally and interviewing local worthies, doing the PA at local events even - she could try volunteering at local sports clubs for example (at my athletics club we always need someone to do the announcing and they could interview the winners too for example).
All of this is way way more important than degree subject if she genuinely wants to get into the media world. It's not easy and she needs to be determined - and show it. Do feel free to ask me any questions - if I can help i am happy to.
Apols for essay-style post!