Wash it out with water with some baking soda in it, then leave some baking soda in a saucer in it overnight.
Should work and certainly won't do any harm.
Assuming, of course, that you have removed the source of the smell.....
is it one of the frost free kind? if so it will have a drain at the back of the fridge at the bottom that lest condensation drain out and evaporate from a tray set over the compressor. 9 times out of 10, in an otherwise clean fridge that smells, that tube has become blocked with mould. What you can do is poke it out with a bit of bendy wire then squirt diluted milton down the hole to clean the tubing and make sure its draining. Give the fridge a good clean out and you are good to go.