I am a self-confessed 'Muso' OP. I was grade 8 sax / grade 5 piano / grade 7 trumpet by 1st year of 6th form and played in so many ensembles/youth orchestras I was out of the house almost every weekend.
I chose to do music with a language at university and went the academic route. For me, this was the best choice as the bit I loved most about music was the ensemble playing (orchestras/wind bands/brass bands/etc). I was a wimpy soloist and my A level teacher suggested I wouldn't feel comfortable at a conservatoire (I agreed). The academic route meant I could still indulge my passion and interest but without the intense pressure of having to be the best soloist. I had a close friend who went to one of the London conservatoires and her entire existance was about being 'the best' in her year, she was under a lot of pressure. The language part of my degree gave me a lot of transferrable skills for work (presentations, communication, linguistic skills, reading body language, writing essays, researching etc). Plus I got to study for a year abroad.
I now work in a completely un-related profession (engineering) as a project manager. I use all my skills from my degree and keep my music going at the weekends in numerous enembles. I decided in my first year of my degree that as long as I had music in my life I would be happy, and that for me, a job in the musical profession wouldn't give me the lifestyle I wanted.
Many of my friends and student peers got jobs in the music field:
Secondary teaching
Primary teaching
Private music lessons (they work long unsociable hours and being self-employed don't get paid annual leave, sick pay, etc)
Publishing assistants for the companies that publish sheet music
Event management (for a major professional orchestra in London, nightclubs, jazz bars, etc)
Ensemble musician on cruise ships (irregular work, but when you are working free board and lodgings and a chance to visit lots of the world!)
Sound technician for theatres/concert halls (if this is the route I would recommend doing the Tonmeister course - it is only run at a handful of universities, competition is high, you need A level maths, but it puts you in the top 10% of sound technicians in the industry)
Marines or military - you can join as a professional musician and you are a paramedic in combat
Other careers taken by my musician colleagues:
Head of IT department for a government dept
Police
Nurse & Doctor (obviously did different degrees, but of 'professional' performing standard, still perform regularly in London)
Actuary
University administration/management
Paramedic
Jewelery business owner
Solicitor (did the 1 year law conversion course after music degree)
I think your DD needs to decide if she wants to do music as a job, or whether she wants to keep it as a hobby. She can still perform at a very high level at the weekends and do another job.
Sorry for the long post!