PHP - beat way to bring array up level

I have this nested arrays

Array
(
    [0] => Array
        (
            [0] => Array
                (
                    [name] => Adam Smith
                )

            [ef] => Array
                (
                    [rate] => 0
                    [superannuation] => 9.5
                    [pportable_lsl] => 0
                    [hours_per_day] => 0
                    [hours_per_week] => 0
                    [weeks_oer_year] => 0
                )

        )
 )

And I want to bring all the child elements to the top level element. For example:

Array
(
    [0] => Array
        (
           [name] => Adam Smith
           [rate] => 0
           [superannuation] => 9.5
           [pportable_lsl] => 0
           [hours_per_day] => 0
           [hours_per_week] => 0
           [weeks_oer_year] => 0
        )
 )

What is the best way to achieve this using PHP built-in functions?