<?php

$full_name = array("first: N", "last: Vidovic");
//var_dump($full_name);
foreach ($full_name as $part_name) {
    $exploded = explode(":", $part_name);
    $make_array[$exploded[0]] =  $exploded[1];
   // echo $make_array["first"]; 
}
print_r($make_array);

Array
(
    [first] =>  N
    [last] =>  Vidovic
)