You mean a third party to deposit btc when betting online casino? Well, the online betting casino.platform has already provided this and having third party is not really necesary. Just create an account in an online casino betting platform.and send your btc to their platform directly to your account. If anything will not going to go well like losing your deposits the. Show your bitcoin.tracker if it is successful or not. The block chain wi tell amd will never lie.
Third party deposit AND withdraw. Actually I am not casino user, but developer. Of course alternative option is to make full node, but at this point I don't want to invest in that.
To sum up what I've found so far, for others in need:
mycelium - no withdraw, only deposit
coingate
bitpay
coinify
gocoin
bitgo - requires 1mln USD monthly traffic
bitaps
However, most of the services are following gambling regulation rules, which needs merchant verification, anti-money-laundry measures etc.. Moreover, from 1st May there is new regulation, which requires merchant verification even for crypto-to-crypto transactions.
I think bitpay can do the job. I already use bitpay but it's for making a payment to buy a product, and it's connected with bitpay.
But I never know if bitpay can be used for another thing and it's a new thing for me.
I cannot imagine how much money we will use to make a full node.
But hey, what kind of regulation that will be needed for the merchant?