Clone Button in Salesforce Account Detail Page
Normally in salesforce Clone Button is not available in Account Object, so if you want please follow the below steps:
To do this first go to Setup | Customize | Accounts | Buttons and Links | New Button/Link and Enter the following in each of the fields:
Label: Clone
Name: Clone
Description: Button to clone Accounts
Display Type: Detail Page Button
Behavior: Display in existing window without sidebar or header
Content Source: URL
Link: /{!Account.Id}/e?clone=1
Once the button has been created it will need to be added to the Account page layout. Please follow the below path to Enable the newly created button in Account Detail Page—-> Setup | Customize | Accounts | Page Layouts.
Edit the Layout, drag and drop the button and then click Save.
NOTE: Cloning an account will transfer Account fields to the new record. However, it will not clone any of the related records.
Reference: https://help.salesforce.com/HTViewSolution?id=000070110&language=en_US