Autocompleting line-item fields in Drupal commerce
If you change the field from a simple text field into an entity reference field, you can create the different clubs as nodes (seems to make sense, since you could then write info about each club on your site). Entity reference comes with a built in autocomplete.

You could also use taxonmy terms and taxonomy reference field instead if you don't want to create a node for each club. Either way should work just fine, as both have autocomplete built in.