Unless you're on the poverty line and/or people have said "we didn't know what clothes to get them, here is some money for you to pick" then no, a child's birthday money goes on nice things and/or in to a savings account.
My 11 year old has around £10,000 in savings, from saving his pocket money/birthday money/Christmas money etc (I would hasten to add that he has my entire family, his dad's family and my husband family so he does "get" more). My hope is that he has a house deposit, can buy a car, can travel etc when he is older without worrying.
I will never use that money to buy him clothes, that is my job as a parent. I buy him his "needs" which an A/W wardrobe is. If he wants something specific as he grows (expensive trainers, designer jumpers etc) then he is free to use his money for that, or on other "want" items.
If you can take yourself to Jamacia, buy new clothes from fast fashion brands constantly then you can use your own money to buy your child clothes.
However this is also the woman who used her child's birthday money to buy a desk that the child, apparently, wanted.