There are many application where i can do trading using bitcoins and crypto currency. It is safe to do so.
I am not sure if you are looking for trading bots or simply mobile applications that connects you to crypto exchanges or mobile wallets that integrated exchanges within their app.
1. Most exchanges now have their own mobile applications available for Android or Apple users.
2. Wallets like Coinomi have ingtegrated Changelly and Shapeshift which allows you to swap/trade bitcoin to other cryptocurrencies.
3. There are also wallets like Coinbase that have their built in exchange (CoinbasePro).
Since you mentioned you're from India, I think WazirX is the most established exchange there right now. Check it out
https://wazirx.com/ i have to invest in an indian clothing online business. It would be useful or not.
Are you planning to trade bitcoin and then use the potential profit to invest in clothing? If so, it's not that easy let me tell you that.