How do I get Path auto to display one item for a field value when there are multiple values available?

Using path auto to create a url structure, I would like the following:

my-content-type/[node:field_restaurant_category]

Note that node:field_restaurant_category can have multiple values, and in my url structure this is unfortunately the case. I have a url now that is my-content-type/t1-t2-t3-t4-tetc

How can I limited the node:field_restaurant_category to be just one and only one term? I honestly don't care which term the module chooses so long as the limitation is in place.

I read earlier that something like node:field_restaurant_category:values:1 should work, or something, but I cannot get any logical configuration of that to work correctly.

Can you tell me how this is done please?