Is there a way of using a separate "Accounts Payable" account for a specific supplier ?

Thanks for posting to the Community about tracking separate Accounts Payable accounts for specific suppliers, Bindu.

The functionality to create a separate Accounts Payable account for a specific supplier's bill or particular utility payments is unavailable at this time. QuickBooks Online (QBO) has its default account to track payable expenses when using bills.

In your case, you'll want to manually calculate and transfer the amount from the default Accounts Payable when you create bills for that supplier by creating a journal entry. 

You can check this article to learn how to create journal entries in QuickBooks Online: Create journal entries in QuickBooks Online.

Also, I'd suggest still referring to your accountant for what specific accounts to debit and credit when recording a journal entry to ensure the accuracy of your books. 

Additionally, I've added this article if you need to modify the entry and help you with the process: Reverse or delete a journal entry in QuickBooks Online.

Feel free to reply to this thread should you need additional assistance managing your bills in QuickBooks Online. I'm always here to assist. Stay safe.