Phone
Haircuts
Clothes
Oyster card
Gifts for family
Trips with mates
Cosmetics
Food if out and about
Without knowing the exact figure (between 40 and 200 could be anything) it's difficult to say but it seems like she has quite a lot of expenses to meet from her "pocket money" - some of which are essentials rather than discretionary. I think you are possibly being U and a little unfair expecting her money to stretch to all this and leaving her without discretionary spending, again without the figure it's hard to tell though! I would do an exact of what each of these items cost over a month.
We have had the same problem. With hindsight, I would either provide a monthly "allowance" for essentials like clothes to be worn to school, coats, shoes, underwear etc, hair, travel, phone etc or pay for them yourself (but set an agreed budget). Then weekly "pocket money" is for discretionary spending like trips to cinema with mates, cosmetics, clothes above the "basics" (like American Horror Story T shirts for mine
). One of mine spends her PM weekly, the other saves it up and buys more expensive stuff.
It's a lot easier this way as you know that her allowance is enough to cover essentials and her pocket money is for treats but it also teaches them to budget and also to save if required. It also prepares them for the real world of being paid either monthly or weekly and how to manage both.
With regards to food out, if we are out and need food over a normal meal time, or we are out at our instigation for a trip we pay. If they want say a Starbucks coffee at 11am in town when we are grocery shopping, they pay.
With regards to clothes, we pay for the essentials like school shoes, trainers/boots, coats, underwear, and basic wardrobe essentials like jeans and tops. We normally give them a set amount for this so they can choose what they would like and say one wants an £££ coat they will pick cheaper jeans, the other wants more £££ shoes and buys a cheaper coat. If they want to buy more "fashion" stuff ( like a Harry Potter Jumper from primark) they use their pocket money. If we have any spare money I will often buy them stuff on Amazon (especially New Look) which I know they will like and just give it to them.
They cost us a fucking fortune but that's having multiple teens for you! DH also has a thing about buying them £££ trainers/shoes as he didn't have them himself when young so I accept this. I like charity shop clothes luckily and we don't smoke or drink so even though we are on a tight budget the DC have as much as we can give them. It's less than a lot of their friends but more than some. They know that we give them as much as we can and they do seem to appreciate it most of the time